Before you go hire a business coach or sales person, enrol in an online course, follow a get rich quick scheme, do this first. Warning, this is a long list of things to do. No easy answers, no quick fixes, but the bare minimum of what you need to do before looking for more help. Remember, people hire who they know, who they like and who they trust. So time to get known.
Jakob Nielsen's 10 general principles for interaction design. They are called "heuristics" because they are broad rules of thumb and not specific usability guidelines.
Usability
10 Usability Heuristics for User Interface Design
Knowledge
How Solo Freelancers Can Land Massive Gigs — Better Marketing