Echoing that a mimi sewing machine might not be the best for larger projects. It'll do you just fine for basic stuff and practicing (as I did use one for a long while :3), but getting yourself a new one might be something to think about as you more on to bigger stuff.
As for what to look for... looking up basic sewing tutorial online would be a great help, especially if you don't have anyone else to teach you different techniques. Though, Home Economics/sewing is good for a start~
If you're looking into making clothes, you should be able to finns beginners/easy-sew patterns in fabric shops etc. It might be an idea to ask the staff there if they can reccommend patterns for beginners