Even though I hate the theme, here is some constructive criticism to help you get you started with your set. "this aint it chief" helps no one lol.
Choose color codes. Look at Pantone, RAL, and stock GMK palettes and choose the colors that closest resemble your vision. Then purchase the physical color samples that they offer so you can see if they look just as good in real life as they do on your screen. Then let us know what you chose.
Determine kitting. Take a look at other keycap sets and see what kitting they used. Use successful sets as a baseline and then gather feedback. Every set has it's own audience and may need the kitting tweaked to benefit them. Consider what you want your base kit to offer and how many other kits you want to make people buy to cover more exotic layouts.
Get a deskmat design going. You can draw something, photoshop some **** together, or hire another artist that will help you show off your vision.
after and only AFTER you have done the above, hire a professional render artist to do renders for all of your kits, mats, and your set on the hypest boards. Be sure guide your render artist to match the colors as closely as possible to your physical color chips. Use several devices to eliminate color errors in this process.
AFTER all of that, go ahead and post an IC. Having a Google Form to help compile your data does help. Use meaningful, unbiased, open ended questions in the form to eliminate bad/uninformative responses.
You will start to gather ACTUAL feedback and you may need to tweak some things. This could be colors, renders, kitting, etc. Be prepared to go back through the first several steps all over again to appease the masses. This may cost money. In fact it WILL cost money. Depending on how many renders and what color books/chips you get, or if you need to purchase a more color accurate monitor, it could set you back anywhere from $250-$1000. Yes if your set does well you will get your money back and then some. If you can't or don't want to take on the risk of spending that much money up front to gather interest, don't. Pay your bills first and come back to it when you are more prepared.
Good luck. There is a Keycap Designers Discord you can join full of helpful info as well as a chat room for hiring artist to help with renders, novelties, deskmats, or whatever else.