Learn how to run a sewing machine, buy some clothes from Goodwill to practice on.
Start with sleeve, pants hems. Darts will be a little trickier, but certainly achievable. For the darts, you can find instructions online
Start with a bigger stitch so mistakes are easily ripped out, then not so big when you know what you're doing.
I've been sewing since I was 7, I'm almost 60, and worked at an alterations shop for a couple of years. Oh, and before that I was a vet tech and saw dogs and cats being sewn up. Clothes are much easier and not as messy.
(When you get a sewing machine, go over some lines on a paper, with no thread, just needle holes to learn and to get familiar with it.)