Number 1: protect your turrets. They are indestructible themselves, but if the block they are on is destroyed, they are lost. My design does put them all on one block but it's iron stone so it's rather strong. I added the sides after a collision with debris took out my turrets. With these solar panels, I think there's enough power for two rare (blue) turret control systems for a total of 6 turrets. I recommend using chainguns for energy conservation reasons.
In 0.8.5 not the hotfix it's possible to target turrets separately from the ship's path by holding control. I use this to sail under enemies while firing all 6 turrets.
Number 2: Not really a shipbuilding tip but stay with allies when confronting enemies. They have quite a few turrets and can take a lot of hits.
To get started, using a mining drone to help fight pirates can get you some starting resources as they drop clouds of materials usually not picked up by the AI until well after they're available for you to pick up.
This is basically my most successful design. It's nice and small and a little slow but ok. I can't verify the specifics because my ship is on a server which is down right now, but it's a stick of blocks the same size as the starting block, of solar, solar, crew, thrusters, and then engine. Then I flatten the block to the minimum based on default settings, place 4 of those on the sides of the thruster, cover the crew quarters and solar panels with more solar panels, and then crew cabins (I think) around the engine. Cover the top with a slab of iron stone, put a slab on each side, and bake at 350 degrees until brown and crispy. The red in the first two is turret placing area, and in the third it is a representation of all turrets firing up.