Recently I've found lots of exercises that improved a lot my playing. Here are some of them:
- On good habits: Hand stretching before playing. Here.
- More good habits: Right hand warm up + CAGED chords by Paul Gilbert. Here.
- On rhythm: Analyzing rhythm and learning from drummers by Paul Gilbert. Here.
- On improvisation: How to improvise taking the most out of a single lick idea by Tom Hess. Here.
- On ear training: "Guitar Simon" by EatSleepGuitar, aka u/circleof5surecanjive. Here.
- On understanding songs: Everything in the YouTube channel Dean Olivet.
- On soloing: How to use triads in solos by Jens Larsen, aka u/jenslarsenjazz. Here.
- Lots of resources by Garret Schmittling, aka u/gschmittling.