Easy Trailheads to find for the Midstate trail are at Wachusett Mountain (in the ski area parking lot), Near Redemption Rock in Princeton on Route 140 and off of the Crow Hill trail in Leominster State forest off of Route 31. I would recommend picking up a trail guide for the Midstate Trail at any Massachusetts EMS or New England Backpacker (in Worcester). You might also want to get a trail guide for the Metacomet-Monadnock trail. Both the Midstate and M-M trails traverse the entire state North to South (or South to North, if you prefer). I recommend the M-M trail for better views and interesting cellar holes and old mill sites, but I have also enjoyed hiking the Midstate. There are also a lot of other nice trails around Mount Wachusett. Have fun.