[dandanisaur]

Imo I'd hold off on susy. Bootstrap is a great start for a beginner abs it's used in a ton of environments.

[excalq]

I took several years away from the front-end to focus on Backend and DevOps, only recently re-upping my front-end-fu. Since I knew CSS 2.0, I found Bootstrap quite easy to pick up and be productive with in about a day, not previously knowing CSS griding. And I found myself saying over again, holy shit where was this back in "my day"!

[subpixel]

Agreed. Also, avoid every other tool that is potentially 'next-gen' compared to what provides the functionality you need. For someone with the goal of publishing web sites, Bootstrap css and js will get you pretty much all the way. Don't worry about moving beyond them until you actually feel you have to.