Personally, I didn't even touch warships until about my 4th game for that reason, so I do understand what you mean. Luckily I actually never ran into a single NPC somehow before then. Then about my 4th game, I deliberately turned off all NPC's, did a multiple faction start all controlled by me, and messed around with some warship designs to get a feel for them before I dove into fighting actual enemies.
So really I would say take it one step at a time. The first sort of ships you will be designing will be things like survey vessels and freighters which are easy enough to get working. They just need some engines and geological sensors or cargo holds. Your first designs probably won't be the best things ever, but then they really aren't expected to be.
I also happen to prefer conventional starts because they ease me into the game without overwhelming me with options from the outset. But that's just my personal preference. Of course, come back here and ask if you need help I think everyone does that quite a lot at first.