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.
good luck