I used to buy broken phones/DS lites/iPods, repair them and sell them to make a few extra bucks. The newer iPhones are not easy to open, the iPods never seem to sit flush because the frame is bent with drops. I have a cupboard full of broken things that seemed like an easy, cheap fix that are annoying me- I get them out, fiddle about with them, get frustrated and then pop them back in the cupboard of no return- iphone 5s, iphone 4, 5 ipod nano, 3 ipod touch gen 4, 3 ipads gen 2,3,4, 3 ds lites, tickle me elmo, a transformer ‘bumblebee’, go pro hero2, ipod touch gen 6, PS2, original xbox (anyone got a dvd drive- they’re rare as rocking horse poo here)
I still use my iFixit pro-kit from 2012/3, waaaay better than a kit my friend bought in europe. Get a fine tip solder station with adjustable heat settings, I had a cheap hot air reflow with a few size nozzles and adjustable temp- it worked fine. A decent “spare hands” type tool for holding things, a good magnifying lamp or a camera set up to a screen for really close work. These things aren’t too expensive actually and can easily be sold on.
start small, practice, practice, practice. Google is your friend and so is iFixit.