You'll find lots of singletrack all over the place, so explore. Pretty much every trail will return you to one of several fire roads which lead out of the park. I usually spend an hour in Mianus before heading to work. These trails tend to be pretty well worn. Roots and mud prevail almost year round.
Rocky spots are also pretty common as a lot of the trails are old riverbeds.
Look out for babyheads in some spots. Overall, this is a fun place to ride. I learned some good skills here on the more technical sections. You'll make up for it trying to navigate the other obstacles. Going in from the parking lot, go right at the fork.