I know this is an old thread, but it’s an interesting topic.
When I made my first OC in 2017, I used Pony Town to get an idea down and then begged others to draw her to perfect her design. Then I decided to just take up drawing myself and had a workable ref a couple weeks later, no tablet needed. In retrospect, I don’t recommend pestering others for OC design help unless they’re a friend and you know they’d like to help. Regardless, there’s a lot of trial and error; even with more OCs now under my belt, it can still be a struggle for me.
As for design tips, take a look at other characters and take note of color saturation, contrast between colors, and such. Some colors certainly go better together than others. If you’re so inclined, there are tutorials and such out there. But do what feels right to you, even if it’s a big important alicorn OC (must all OCs be mundane?), before making sure you check boxes of design rules.