Basically, I want to ask whether it's better to improvise (over 12 bar blues in my case) or just to learn the solos in songs. Played with a backing track today for the first time, and discovered that I can somewhat play a lead part with the pentatonic (was playing in A if that matters). I know to some degree that this is my decision to make, but what do you guys think suits a semi noob best?
both, start with learning other solos so you always have a lick up your sleeve
If you play someone else's solos you'll get a feel for what's commonly utilized, and how it's done. It's important though to be able to do it on your own as well. Always think about why whatever notes you're playing sound good over whatever progression is in the background; knowledge and application of that knowledge should be your ultimate goal, and it would probably be best if you combined both working with 12 bar blues and learn the ways others solo and use phrasing, outside of just the blues scale. good luck