Testing and Revising Your Material
The best way to test your material is to perform it. You can't create comedy in a vacuum. You need real-world feedback to see if it's funny or not. See what works and what doesn't, then make changes accordingly. The more you get out there, the faster you'll improve; it's that simple. Woody Allen once said, “Eighty percent of success is showing up” and it's true.
If you perform an entirely new set every time you go on stage, you'll have a lot of jokes, but you won't have strong jokes. Never look at a joke as “done.” It can always get better. Each time you perform it you'll come up with distinctions that will improve your material.
You can ask friends whose opinions you value to look over your writing or be a sounding board for jokes. Be careful trying out material on other comics, though. Sometimes your styles won't mesh, or they might see your material through their filter. If they wouldn't do the joke, it's hard for them to see if it would work for you.
Lots of people will try to give you advice. If you respect someone, listen carefully to what he has to say. If you don't know the person or don't have a lot of respect for his opinion, just take it with a grain of salt. A lot of people will tell you how they would perform the joke, but that's not necessarily useful for you. Ultimately, you are your own best sounding board. Trust your instincts over the opinions of others.