I am wondering what all the common ones are.
1. If possible and able, take a shower and wear clean clothing.
2. Light a lamp - this is an invocation for inner light to come alive eventually" and sit quite before a photo or idle of any God or your parents and close your eyes and just chant some thing which is one syllable like "OM" or Yu etc. This is to shut your ears hearing other sounds. By shutting your eyes you have avoided light and images, but to shut the ears not hearing anything is difficult and that is why this is done. When Chinmaya gave a 40 lecture a father of my friend told me, that he was skeptical. The place was near Mount Road near Gemini studios. After about 1 week for a fraction of a second, he did not hear any sound (buses use to run constantly), three weeks later for 5 minutes he did not hear any thing, and aftet that for about 10 minutes he did not hear any thing. So he told me that Chinmaya will say " Asaagpham, Asanghoham, Saschitanandogom.." So, he taught me and even now for 10 minutes I am at bliss.
3. Then offer even a drop of milk or water to ancestors as a token of gratitude.
4. The offer 10 hands full of water (Paathyam arkyam) invoking "to all my departed relative's souls, I offer this).
That is all. Then as far as possible do not lie or shout or curse any one.
In the night recall all those who have touched your life and pray to them to forgive you and enlighten you. Om tastat Krishanyanamaha - every thing to Krishna.
This can be done in any country, any time, anywhere. No mantram is needed. You will see peace of mind slowly taking over your life.