o7 welcome back. The good news is there are a ton of ways to make isk with a combat skilled character like the one you have.
you sound like you are in a pretty similar spot to where I was a few years back. About 4 years ago CCP introduced a new kind of mission called burners, these typically have a strong NPC that you have to fight in a frigate. There are also a few cruiser sized missions. I like these missions as they use all the PVP skills you have probably developed. There’s a big thread with a lot of fitting suggestions over here:
Beyond that I mostly trade and build stuff. Most of my trading began with just selling mission loot and LP, and well I just keep trading more. These days I mostly just trade. And as far as building stuff goes just look at items that are useful, and build some spreadsheets to figure out how much it costs to build. I used the spare character slots on my accounts to build more stuff. A few months with multiple pilot training Certs plus some injectors and now each of my accounts has 30 build slots and 10-20 science slots.
I’d suggest you look at Blockade Runners (BRs) or Deep Space Transports (DSTs). these should give you some good hauling flexibility and should hopefully avoid being an easy target. A BR is cargo scan immune, aligns pretty quickly, and can fit a covert ops cloak so that helps a ton evading gankers, but I suggest at least enough tank to have 15k+ ehp as some people will play the BR lottery and hope you are hauling some high value goods. DSTs carry a bunch more and are a bit slower but can fit a lot more tank, also you can use the MWD+Cloak trick to move around. Anything bigger and I use courier contracts. People will move big loads for cheap.
Personally I’m pretty against selling characters, and even more so against extracting to inject new ones as there are some harsh diminishing returns, unless you have a very strong reason. Since you just got back into the game I’d hold off on doing anything like that for a while.
Buying tags 4 sec would be the fastest, probably worth taking at least some shortcut there as some of the tags are pretty cheap, but also it’s not that hard to grind sec status if you don’t have a lot of isk available.