I've been through thread after thread of help topics and I can't seem to find any legit help with making money. I've tried just about everything, but everythinng is incredibly vague. Long story short, I end up spending all my money on fuel because I aimlessly fly around. I can't afford mining gear, I can never find assassination targets and I can never find destinations to trade resources. What am I missing?
If you're at the very start, then you're probably still in a cheap, low-end Sidewinder. You'll need to upgrade that some if you want to progress (you probably don't have enough credits for a new ship). Try replacing the Frame Shift Drive (easier to make longer jumps/longer routes), buy a Fuel Scoop (no need to buy fuel), Powerplant (more power available); and the largest cargo bay you can (it's going to be small anyway, in a Sidey).
To do that, you'll need money. I'd stay away from combat missions if you're still in the Sidey, try doing some easy haulage missions for now. They don't cost you anything, and they're low risk. Also, keep an eye on the Active Community Goals thread here. Sometimes, if you get in at the right time, you can make millions of credits in just a handful of jumps. Ask on that thread too, they might be able to advise if/when there's a suitable CG happening.
Trade can involve a lot of jumping around if you don't have an exact plan, and you don't want that in the Sidewinder. Rares trading even worse. Smuggling / Robigo missions worse again, I'd imagine. So build up your credits with haulage, then upgrade, and you can take on more (mining, combat, smuggling, exploration...)