Avoidance is a combination of high burn and judicious use of sustained and emergengy burns. I’d keep a minimum fleet burn of 9. The navigation skill that gives +1 burn helps a lot here. Use ship systems like militarized subsystems and/or augmented drive field to increase burn of slower support ships.
Remember that kicking off a sustained burn involved a stop and pause, so if you need to get away from a fleet and they are already close and moving fast do not hesitate to emergency burn and get the hell out of there. If you are already in a sustained burn but you need to change direction fast, toggle sustained burn off and on.
In order to not get jumped, as soon as you see an unknown fleet pause and assess so if you decide you need to avoid. Even if you can’t positively identify the fleet yet, the types of ships in it usually gives away what it is.
If you are operating in a system with a nav bouy, hack it (or take it over) for a +2 or +3 boost to your burn. It can make a huge difference.
Keeping your sensor profile low also isn’t a bad idea but isn’t nearly as important as the ability to run away. The five ships with the largest profiles are what counts. Civilian ships have much larger sensor profiles. Militarized subsystems and/or insulated engine assemblies can mitigate this.
The only time salvaging a ship is worth it is if you have no other means to get that ship, or if your holds are full and temporarily need another freighter to hold the spoils of your activities. Removing a defect from a ship costs more than buying the ship new. So for the basic support ships that are available at most ports just buy what you need.
As a general tip I cannot recommend enough the strategy of hanging around systems with system bounties or ones under pirate attack and finding large ongoing battles to get involved in. You can make a ton of money and make big improvements in faction relations in very little time. It is also great piloting practice to fly around with just your flagship or a small detachment looking for opportunities to pick off ships. If things don’t go well, just go hide behind your allies.