Upacharas refers the articles offered to the Lord in worship. The upacharas are different aspects of service.  These are the items which are offered to a person to show respectful treatment.  All elements should be offered with love.

64 upacharas
16 upacharas
10 upacharas
5 upacharas

Numbers of Upacharas:

In daily worship, one usually offers  sixteen  upacharas to the principal deity and more if the deity is in a temple. Other deities may be offered ten or five upacharas, depending on ones facilities and time.  It is to be understood that the offering of upacharas should be preceded by the purificatory rites of purvanga karma and followed by the concluding activities. The upacharas are given below.

One will notice that the list of ten upacharas omits the elements of the bath, while the list of five upacharas omits both the bath and the preliminary welcome with asanas, padyam etc.

Some authorities include svagatam (welcome / greetings) as one of the sixteen upacharas and omit upavita (sacred thread), while others include upavita and omit svagatam.  For this reason these items are in parentheses.

Sodasa Upachara    Dasa Upachara      Pancha Upachara
16 items                    10 items                   5 items

asana
(svagatam)
padyam                     padyam
arghyam                    arghyam
acamaniyam              acamaniyam
madhuparka              madhuparka
acamaniyam              acamaniyam
snaniyam
vastram
(upavitam)
alankara
gandha                      gandha               gandha
puspa                        puspa                puspa
dhupa                        dhupa               dhupa
dipa                           dipa                  dipa
naivedyam                  naivedyam        naivedyam
pranama

Three upacharas:     Two upacharas:       One upachara:

gandha                      gandha                     bhakti
puspa                        puspa
naivedyam

Usually temples can offer more than sixteen upacharas without difficulty.  64 upacharas which are offered throughout the day  are listed in Hari Bhakti Vilasa and Chaitanya Charitamrta.   The sequence has been rearranged and divided for better understanding.  This will give some idea of the opulent type of service that should be offered in the temple.
 

Early Morning activities:

Waking the deity with vedic verses, praises, instrumental music.
Offering a twig for brushing the teeth.
Offering mangala aratika.
Shouting jaya on seeing the deity.
Offering pranamas to the Lord before entering for puja.

Offering the Main Upacharas:

Inviting the Lord (avahana), offering him a seat (asana), and making him comfortable (svagatam).
Washing the Lord's feet (padyam).
Offering arghyam as a sign of welcome and respect.
Offering water to wash the mouth (acamaniyam).
Offering madhuparka, then water to wash the mouth.

Offering the Lord shoes so that he may come to the bathing place.
Cleaning the Lord's body with a damp cloth to remove old chandana etc. (murti samskara).
Rubbing the Lord's body, especially the head,  with fragrant oils.
Bathing the Lord in flower water.
Bathing the Lord in milk.
Bathing the Lord in yogurt.
Bathing the Lord in ghee.
Bathing the Lord in honey.
Bathing the Lord in sugar.
Bathing the Lord in water consecrated with mantras.

Removing oil, ghee, etc, with flour, then warm water.
Wiping the Lords body with a soft, dry cloth (anga vastra).
Dressing the Lord in upper and lower cloth.

     Offering gayatri thread (upavita).
Offering achamana again after dressing.

     Arranging the Lord's hair.
Decorating the Lord with bracelets, necklaces, rings etc.
Offering kaustubha and other wonderful jewels.
Offering various colors of clothing, belts, turbans, capes etc.
Offering flowers to the Lord's lotus feet. Applying gandha to the Lord's feet with a Tulasi leaf.

Offering incense.
Offering lamps.
Removing inauspicious influences, the glances of evil persons by mustard seeds etc.

Offering naivedyam.
Offering spices (mukha vasa).
Offering betel (tambulam).
Offering a couch for the Lord to relax in.
Offering gandha again and decorating the Lord's body with tilaka designs.
Offering the Lord a crown.
Offering varieties of flowers and garlands.

     Darshana:

     Offering a mirror.
     Offering chamara and umbrella.
     Singing.
     Playing instruments.
     Dancing.
     Offering aratika.
     Taking deity to a special mandapa.
     Bringing the Lord back to his throne.
 

     Bhoga Offering:

     Offering foot wash, mouth wash again.
     Offering another meal while burning incense.
     Offering betel, then performing aratika.

     Concluding Puja:

     Recitation of verses (stuti)
     Circumabulation of deity (pradakshina)
     Pranamas.

Touching ones head at the lotus feet of the Lord (astanga pranama).
The taking charanamrta and flower prasada on ones head.
Taking the food remnants of the Lord.

     Night service:

Sitting at the feet of the Lord ready for service.
Making a nice bed for the Lord, with  soft cloth, flowers and nice scented powders.
Offering ones hand to the Lord, and offering him his shoes,  to bring him to the bed.
Receiving the Lord at the bed with great festivity.
Washing the Lord's feet, then drying them, offering gandha, flowers, betel, condensed milk, fan.
Having the Lord lie down in the bed and massaging his lotus feet.

The offering of upacharas is sometimes divided into groups (Padma Samhita), according to the change of location of worship.

First comes the sapraya asana, where the Lord is worshiped by offering asana, svagatam, foot wash, arghya, mouth wash, madhuparka,  mouth wash.  The Lord is then offered shoes and led to the bathing area or snana asana, where he is offered tooth brush and tongue scrapper (if not offered when first waking the deity), where oil is rubbed on his body, and where he is bathed.  After the Lord is dried, he is offered shoes and led to the alankara  asana, where he is offered cloth, upavita, ornaments, flower decorations and garlands. After this the Lord may go out of the temple on procession in a palanquin. This is called yatra asana.  This is sometimes done in meditation.  The Lord is offered shoes and invited to the bhoga asana, where he is offered asana, padyam, achamana,  arghya, and water for his hands, a meal, drinking water, water to wash hands and mouth, achamana,  tambula.  The concluding elements  of chanting mula mantra japa, offering it to the Lord, asking forgiveness for offenses, circumambulation and obeisances is called mantra asana. Putting the Lord in a bed to take rest is called sayana asana.

Symbolism of the Upacharas:

The offering of items are sometimes conceived as an offering of all the elements and senses in the service of the Lord.

asana: lotus of the heart
padyam: water in the form of amrta
arghyam: mind
achamaniyam, snana: armta
cloth: akasa
gandha: sense of smell
flowers: chitta
incense:  five pranas (pranaya, apanaya, vyanaya, udanaya, samanaya)
lights: fire
bell: dhvani
naivedya: amrta
chamara: air
gita: sound
nrtya: activities of the senses and mind
mala: flowers of consisting of absence of maya, egotism, attachment, vanity, delusion, arrogance, enmity, perturbance, malice, covetousness; and possession of ahimsa, sense control, mercy, forgiveness and knowledge.

Substitutes for Upacharas:

If any of the above items are lacking, one should still perform worship, by substituting flowers, raw white rice, barley, Tulasi  or pure water for the articles.  At the time of offering the article which is lacking, one should say the mantra for offering that article and meditate on its presence as one offers the substitute (water etc). The water or flowers may be discarded in a vessel for that purpose. Thus even the poorest person, with only a few copper vessels and pure water, by use of mantra, meditation and devotion, can worship the Lord in full opulence and receive the greatest mercy from the Lord.

Respect for the  Upacharas:

The Lord's clothing, bedding, slippers and everything required as an ordinary necessity, are all transformations of Shesha Vishnu, the expansion of Sri Baladeva.  Thus the cloth and other paraphernalia of the Supreme Personality of Godhead are but other forms of the Supreme Personality of Godhead.  Everything connected to the Lord is worshippable.

"According to etiquette things used by Krsna should not be used by anyone else.  Similarly things used by the spiritual master should also not be used by anyone else.  That is etiquette.  Whatever is used by Krsna or the spiritual master is worshippable.  In particular their sitting or eating places should not be used by anyone else." (A.C.Bhaktivedanta Swami Prabhupada. Sri Chaitanya Charitamrita Madhya-lila. V.6p.119.)

Method of Offering:

One should name the article and say the mula mantra, while sprinkling the article with arghya water.  Some articles (dhupa, dipa) have special verses which should be recited at this time.

One may then show the upachara mudra.

One should then present the article to the Lord saying, samarpayami.

Some authorities say that the Lord does not accept any article without Tulasi, and therefore they also place Tulasi on dhupa holder, lamp, etc., before offering. I personally do not suggest this, but still it is there.

One should ring the bell while offering arghya, snaniyam, dhupa, dipa and naivedyam.

According to some tantric scriptures, one should not show ones finger nails while offering items.  Therefore one should always offer items with palm turned upwards.  The items should be offered by the right hand thumb and forefinger (except gandha, dhupa and dipa), while the left hand touches the right arm, elbow or fore-arm. When offering an item one should not directly hold it or pass it over the deity's head.

After offering an article one should wash the hands before offering another article. It is important also that one does not use such items as the offered incense to light un-offered lamps, or take water from the arghya to purify the flowers for instance.

More on upacharas - details on each upachara: