In the light of the recent "proof wars" in symplectic geometry (in which some groups contend that proofs given by some other groups are wrong) I thought it would be good to have some basic guidelines (or best practices) for writing proofs in math papers as a community wiki on MO. This would be specially useful for the newcomers. 

I don't just mean individual proofs but also the whole interconnected web of arguments in a paper. I think this is important as modern math papers tend to be long and highly complex and therefore difficult to referee.