Often, I find playing finger-style more challenging than strumming, so I emphasize a lot of classical guitar repertoire and left/right-hand exercises from that genre.
The line between 'just strumming' and 'just fingerstyle' has blurred with not only hybrid picking but percussive guitar (incorporating guitar slaps, taps, etc.) into a very exciting amalgamation of styles.
Artists such as Michael Hedges, Don Ross, Preston Reed, and Andy McKee are very entertaining and technical, and challenging to replicate. Check out this beginning primer by Petteri Sariola, there are many others. One of my all-time favorite percussive examples by Andy McKee is Drifting, or Jon Gomm's Chaka Kan.
The left-hand studies by Giuliani are invaluable for developing right-hand tone, and left-hand sensitivity (not pressing too hard). Here's an excerpt.
Exercises 1-3 in TAB
TIP 1 - Learn to read guitar music, there is no substitute.
TIP 2 - Learn how to play finger-style (finger pick). I recommend using classical guitar technique and its repertoire to train your right hand, especially its position. Bad habits in this area are very difficult to fix as your teacher.