Hello First of all, I don't think you should give up. All of us here have done bad sigs and better sigs. I have used PS for quite some time now and even though I have the excuse of the practise (I don't have time to practise that much) , many people still criticze my sigs.
Because the reality is..you can't just please all the world.

But there are some general things that can help you to reach a level of harmony between colors and visual of the sig.

Right now my advice is: just keep trying, your work will get better evry day and you'll know what are your mistakes and what you're doing wrong or not.