What I’ve found with non-stretch fabrics (like quilting-weight cotton) is that the easiest way to cut straight (into say, a square) is to run a piece of wool across the piece of fabric and then chalk on a line to follow. If you’re trying to cut around a really precise pattern, I would suggest getting a fairly good pair of scissors - they’re really sharp and cut a good, sharp line, so you don’t end up wiggling the scissors around trying to get them to cut, and ending up with a line that isn’t straight. Also, use the whole length of the blade of the scissors. If you just use the very tip of the scissors like a lot of people do, you can get a messy line. Open the scissors up the whole way and cut right to the tip of the blade. 

I hope this is sorta what you were looking for. If you want to know anything else please let me know!

Thanks very much :) I hope you like it!

I honestly think the best thing to do would be to get a professional to do it. It might be possible to do it yourself, but you’d probably have to totally resew the zipper and it’s crazy hard to sew through leather/other materials used to make boots. Look around though, they might not be that expensive to fix. Ask a few places what it would cost before you buy them, because if the discount is huge it might still be cheaper than buying a non-discounted pair :)

The summer’s just starting up for me! :P

You’re welcome! Just let me know if you want any specific tutorials, especially machine basics, because I’m not sure how much my followers already know >.<