A common mistake is with selecting an overblown "corporate" title when you're tiny.
For instance I'd suggest "Founder" rather than "CEO" - speaking from personal experience here:
When I started my first business in the late 90’s I listed my title as "General Partner" (it was an LLC, made sense to me) and had more than a few people raise eyebrows, smile knowingly at the amateur hour that had just handed them a card.
My other favorite ambiguous but accurate title that's not overblown is "Business Development" . . .