>>419597I've made a few things with a sewing machine. Namely my underquilt (pic related).
Learn how to reset the bobbin and thread the machine. Watch a few videos before-hand but you'll pick it up pretty quickly when actually doing it yourself. There are a few different settings on the sewing machine and they have their different uses, but you probably won't use all of them. I only use like three different settings on the sewing machine.
Work out how much thread you'll need for your project and then buy double that. Mistakes happen and it's always better to have too much than to have too little. Buy spare needles for the machine; these only break if you're too rough with the machine or trying to sew something which the needle can't handle, but you don't want to break your only needle and then wait 2-3 days for another to arrive from eBay.
Lastly, plan your projects detailed enough to begin with that you know what you're doing, but don't feel you have to stay completely rigid to your pattern. Obviously be appropriate, but if your pattern says that you should be doing one thing and then it just doesn't measure up in practice, don't be scared to make the necessary modifications.
Also, learn how to sew by hand. For leather I use saddle stitching exclusively and for fabrics I usually do back-stitching and if I think necessary I'll do a blanket stitch as well (both of these techniques can be found easily through google, but I'll add two links to the end
Backstitching:
https://www.youtube.com/watch?v=rZ_wVC84UmMBlanket stitch:
https://www.youtube.com/watch?v=Wcf9iJHST94Replacing the bobbin on a sewing machine:
https://www.youtube.com/watch?v=-T2-ZFZDQ-YThe other three videos I've learned from myself, I found the sewing machine I used quite intuitive for threading it, so I can't recommend any videos myself and all the ones I'm seeing are like 6 minutes long up to half an hour, which is fucking ridiculous because it takes about 30 seconds.