When designing for a big project or just that final rush at the end of a project, it's always good to make sure you haven't missed anything. I find it's the small things I stumble over more than anything big. So without further ado, here is the checklist:
Padding Is the padding right? A good way to make sure the padding is correct all the way around if you don't have a ruler tool handy, and I find it a bit quicker too. Make a square with a transparent fill and a heavy stroke. Make sure the stroke is the amount of padding you want, and then align off the stroke. Remember to delete the stroke!
Align Using guides, align your text and imagery off of each other. There is nothing worse than something just out of alignment. So the best way to make sure this is working id to use guide-lines to save yourself the horror.
Reread the Brief! This is probably the most important. When working I always make sure to have the a checklist of requirements in the document I am using. Before sending it off for review, reread the checklist and make sure you haven't missed anything small. It can also remind me of the format they want it in.
Rule of Three This is context based, but I like to give an option of three designs when sending out for approval. If you're making a video, don't bother, but if it's a single output maybe make some variations. If this is a repeat client, I like to sneakily include an old design. I might change the colour, or some of the content to make sense. It saves you time and most of the time the client won't remember.
Check the Copy My work often involves using mockups to show prospecting clients, and if you're not careful, it's easy to forget about the copy from the template used. Luckily I've yet to send the wrong copy to an actual client but it's a good thing to keep an eye on. Whether it's a spelling mistake, or the copy you're using is outdated. Hope this helps!