I'll give a few more steps as I thought it would be more self explanatory.
1. Find some ships to salvage. You don't need to meet it's salvage requirements at all.
2. recover the ships, and immediately mothball them! This prevents all costs outside of hyperspace (still uses fuel in hyperspace) as long as you're fast, you will not receive any penalty for insufficient crew.
3. Take them to a base where you can repair your fleet.
4. At the fleet screen inside the base, strip down and un-mothball one ship that you have sufficient supplies to repair.
5. repair in the text dialogue (crew is not required while docked)
6. Scuttle the ship for a full refund of supplies and an equal amount of free fuel.
7. Un- mothball the next ship and repeat!
I've made over 200,000 on free fuel since discovering this!