Sounds like you are in the north-east. I live in Kingston, NY and herp the surrounding areas. I almost always find atleast one species of snake every day i go out. Yesterday i found a nice sized ringneck, saw a large waternsake coiled in some leaves.. and actually stepped on a big black rat snake! Didnt realize untill he started rattling his tail, but he quickly sped off once i "jumped". (thought i was on a copperhead)
Garters - Almost all situations.
Water snakes - under or on rocks near the more remote ponds.
Milks - under rock piles near "wild" ponds and lakes where there are many hemlocks. Also in old barns and buildings with trash, etc.
Black Racers - near ponds also, especially in old, large stonewalls right on the water. See them alot in spring.
Black Rats - same as racers but only in specific areas, ussually in areas surrounding mountains and hills with rock outcrops and lots of hemlocks.
Ringnecks - Under stones in most any type of woods, ussually more moist situations. Also in stonewalls.
Timber Rattlers - At there dens, site specific, but ussually wedged under rocks.
Still havent found any hognose or copperheads, but i know of some good spots for this fall. To sum it all up.. (in my experience anyways), remote areas with water, rocks and hemlocks.. and you cant go wrong.
Hope that helped a bit..
O H