Do as thou wilt shall be the whole of the Law.
The Book of Going Forth By Day (The Egyptian Book of the Dead)/The Scroll of Ani is an excellent source and has multiple prayers to Thoth. My favorite prayer from that source, which is excellent for offerings, “I am thy writing palette, oh Thoth, and I have brought unto thee thine ink jar.” It is a prayer I use at least three times per day.
Just go to the direct sources and you will find plenty on Thoth. The Coffin Texts, The Pyramid Texts, just about any sacred scroll is going to have prayers to Thoth as he was the god of writing and magick and his priests wrote most of it.
Love is the Law, love under will.