What are the 16 upacharam that you could offer GOD?

Following are the 16 steps involved in a hindu-puja.

1.Aavahanam
2.Dhyanam
3.Aasanam
4.Paadyam
5.Arghyam
6.Snanam-Abhishekam
7.Vastram
8.Yagynopavitam
9.Gandham(Fragrance-Spray, Flowers, Adornments)
10.AdhaangaPuja
11.Dhoopam
12.Deepam
13.Naivedyam
14.Tamboolam
15.Neeraajanam
16.MantraPushpam

1.Aavahanam
This is an invitation to God to come to your Mandap or Puja Mandir

2.Dhyanam
This is the meditation sloka that you would chant visualizing GOD while meditating upon him. You could ask lord to come to your house in the form of RAMA, KRISHNA, VAMANA etc...It is up to you how you meditate upon him and he would come to your place in that form for you.

3.Aasanam
You would offer him a seat generally made with 9 types of gem-stone and is fully adorned with GOLD. Again, this could be visualized or meditated upon and you are not expected to make one for him...It is well and good if you could offer him a seat like that.

4.Padyam
Give him WATER to wash his legs.

5.Arghyam
Give him WATER to wash his hands.

6.Snanam-Abhishekam
You would request GOD to take bath. Vishnu loves bath in "Panchaamrutalu(honey, cow milk, cow ghee, cow yogurt, sugar)" followed by Suddhodaka snanam(holy bath with clear water)

7.Vastram
You would offer GOD new clothes after his holy bath

8.Yagynopavitam
You give him the holy thread to wear around his torso.

9.Gandham(Fragrance-Spray, Flowers, Adornments)
You sprinkle some fragrant scent(gandham) and sandalwood on him. "Vishno: Alankaara Priyaha:".Lord Vishnu loves to be adorned and he loves it if you do it with Tulsi and flowers. 

10.AdhaangaPuja
Every part in his body is praised with a mantram. So you could visualize here that he is seated in all the resplendent adornments, wearing the new silk clothes you have offered him in his majestic seat with a sweet smile filled with all the affection he has for you and eager to see what you would do next...This is when you would describe his every part of the body(useful for meditating upon him) with a hymn.

11.Dhoopam
You offer him agarbatti and Dhoopam(Fragrant smoke) from agarbatti

12.Deepam
You show him the lighted deepam. A lighted candle is the easiest form that our mind can contemplate on for meditation. So our elders have prescribed this step for letting the mind slow down a bit and meditate on god.

13.Naivedyam
You offer him food that you have prepared for him. This is when you get an opportunity to thank him for all that he has given you by offering him back from his own wealth.

14.Tamboolam
Now that GOD is full with your offering, he needs tamboolam for digestion. He is so full that he is not ready to move out of your mandap/altar even an inch.

15.Neeraajanam
You give him mangala haarathi with camphor. You would then take the najar off the lord by giving him aarathi and saying him "Managalam-May good things happen to you"

16.MantraPushpam
Pray him with mantra-pushpam "turning your manas into a flower with a hymn and offer at his feet" and bid him good bye only to invite him to your puja again.

These are the 16 steps that are followed in a hindu puja. These steps are prescribed in this order because this was how our special guests were treated at home. So it becomes easy for us to visualize our lord as a special guest who came to our home to accept our prayers and bless us. Following this prescription is just for showing our commitment to learn how to pray and another affirmative assurance for ourselves that we are heading in the right direction.

The lord doesn't demand any of these but it is for our satisfaction that we do all these steps. It is like a practice session for us to get used to this style of prayer which could later take us to "Manasa puja" which is "Puja through meditation where you do all these mentally in your mind/heart".



source:
http://bhaktipedia.blogspot.sg/2007/09/what-are-16-upacharalu-that-you-could.html