Number the checkpoints :)
Now that I've completed the French tree, every day I go through and review my weak lessons (pretty much everything after the last checkpoint...yikes!). The tree is so large that it takes a while to find my last stopping point. It would be great if the checkpoints were numbered, Checkpoint #1, Checkpoint #2, etc. Also, what might be even better would be if Duolingo could remember the last lesson location on the tree, instead of dropping us back at the beginning each time. Thanks to Luis and the DL teams for all the great work!
p.s. abandoning the heart system has made it so much easier to keep up the motivation, love it.