If you are looking for a modern account, i would advise Duminil-Copin: < It's in french but the exercises are very good. Also Ariel Yadin: < exercises are also very good. Both of them are from the same school of thoughts. A book is dealing with a more abstract setting and has become a Bible (for me), soon to be published at CUP: < The Bollobas/Riordan is also a standard reference in percolation, with good exercises.