get your clients final input and approval before you publicly post your work, if possible!
i see it a lot on da especially that people post stuff in the descriptions to the effect of "note me if you have any problems/want the full res/transparent file," you should probably be providing these things to your client while you are still working with them!
communication is important, dont skimp out on that if you can. it shouldnt have to be your clients responsibility to chase you down and ask for their paid work from you after the fact