best wishes for you/to you

if you are writing a letter, i think it would be more appropriate to write best wishes in the end,,, actually, i think best wishes, and only this is suitable, if you want to say something similar to best wishes to you or for you, i would suggest you to say, with regards to you. =)
hope this helps =)

Both are correct.
If you use to,it focuses in what you are doing.
If you use for,it focuses the letter / .... addressed to where.

best wishes to you!