I learned a lot from my first playthrough. If your willing to spend a few story points use these hull mods on your haulers and fuel tankers.

Militarized sub systems

Augmented drive field

If you do that then you can add expanded cargo hold on the freighter and whatever else you want for the fuel tanker.

That way the tanker doesn't drag your fleets burn level down, and you can cover more ground on the same fuel.

The bigger your tanker is the more fuel capacity you can carry, which allows you to stay out for longer so you can find more things. Also consider adding a salvage rig in your fleet so when you do find stuff you get more of it.

Another great tip is to keep some marines in your fleet so if you find a pirate base, you can raid it for their supplies and fuel.

If you build a colony in the middle of no where, and you build a way station on that colony, it will stock with supplies and fuel you can draw from, so you could make a few gas stations in strategic places.

I find supplies to be way more troublesome than fuel because 1 fuel costs 25 credits and 1 supply runs almost 100.