One thing that might help is taking some Sail & Power Squadron Courses.
Some insurance Co's look positively on those that take the initiative to learn before heading out with a "new" boat...also they usually offer discounts for courses and USPS membership
USPS is a great resource for those getting started as well as those wanting to expand their horizons Knowledge + experience builds confidence.
You will also gain a network of people with similar interests.
I've also known insurers to require one to use a captain initially and/or to have a captain certify they believe you're adequately knowledgeable to start on your own. I knew one person for whom that was one day out with a good training captain.