I’m not a huge InDesign fan either, but it’s an essential component in the CC group. It’s perfect for multi-page projects and for gluing various things together, but whenever I can get away with it, I’ll use Illustrator instead. Between Illustrator, Photoshop and InDesign, I use InDesign the least. The mix probably depends on the kinds of jobs a designer works on, though.
As for practicing, everyone learns differently. I learn best by just jumping in and figuring things out. Others learn best in structured classes, working through tutorials or watching videos.
YouTube videos can be really hit-and-miss. If you can find some good ones, great. Much better, professionally done tutorial videos can be found on Lynda.com, Pluralsite.com and Skillshare.com, but they cost money. Sometimes, these sites offer some good discounts for students or free trial periods.