It is a benefit for both the Buyer and Seller to lay out clear instructions before the gig. I have had the experience lately with a buyer that continuously gives me the gig requirements and then asks for revisions adding in things that are second hand thoughts. It is an email template gig so they are adding in text that they want, but they could have given me that text before I started on the project instead of needing a revision.
Make sure that you have your content or instructions together before ordering a gig. Things like designing take a lot of time. Going back and fixing things after the work is complete is sometimes like asking a seller to do the job over again.
If a seller does a good job for you, it is also nice to leave a tip as well. They will be sure to keep up the good work when you go back to them.
Those are my two cents of advice.