I'm going to just assume that dreadnought means an exorbitantly high mass. In that case there's a few neat tricks one can use to maximize a large ship's strengths and minimize it's weaknesses.
The first point is going to be power, which is going to be your backbone. I've seen a few ways people have done power in large ships, and they all revolve around getting past the 1 million bonus power regen soft cap.
My favorite is to focus on power capacity, since it scales up with group size. I always have a ton of the cheap, glowing, green power capacitors because they enable large ships to have that dreaded 1 shot KO alpha strike or even temporary cloaking capabilities. Think of a high capacity as having infinite power for x seconds and it's uses will become apparent.
Another trick is to have docked reactors; separate ships with just enough power blocks to reach the regen soft cap and logic-activated power supply beams docked either onto or into a large ship to give it lots of power regen with a low cost in space. It can be very effective even in smaller capital ships but suffers from the same weaknesses at turrets. Unless you make them substantially larger and more expensive then they are going to be defenseless targets for just about any size of enemy to pick off. Heck, if someone lets loose a swarm of heatseeker missiles you could lose lots of them at once.
If your ship's design and shape has an area that isn't likely to be shot, it would make a prime location for externally docked reactors for a huge boost in power regen.
The most common one is simply spamming bricks of power generators all over the place. It might seem noobish, but it's effective considering large ships have the space needed to brute-force their way past the power soft cap, it'll just take tons of space. A 100x100x100 cube of power regen blocks will give you 25 million regen. Yeah, that's a ton of space, but compared to weapons and shields power regen blocks are dirt cheap, so space is pretty much the only cost.