NEVER GET A KINGSNAKE AS A FIRST SNAKE NOR MILKSNAKE
they are very hard to handle, and can easily bite. i would suggest:
florida green snake
there might be more, but those are the ones we had before and nothing ever went wrong.
though getting a hognose
is pricey, the good thing about hognoses that they rarely ever bite, they'll bluff what i mean by bluff is that instead if taking a grab of you they some what head-but you. bad thing is there hyper and they have a certain poison that swells where you have been bitten, it's not fatal. females reach to 4 feet, and male reach to 2 feet.
are easy to find and really calm with you, sometimes there mean. we only have one out of like 5 pythons we have one mean one because she isn't used to people and she is just a hatchling. but there big reach to like 5 or 6 feet (i forgot around that) though females will always be bigger.
there slower and won't go crazy all over the place when you hold them, because since they have a bigger body they won't move as much.
these are great beginner snakes, not as pricey as the other two but they reach to 6 feet as well (for females). they are really nice and gentle, but they are energetic since there body is more slim. they have beautiful colorations that don't reach to like $1000 like hognoses or ball pythons. we have a juvenile, and she is really loveable, though kinda hyper.
i don't know the average size of them since i haven't had them for a long time. good beginner snakes, you could also feed them crickets or worms unlike other snakes eat mice, toads, etc. so there more simpler for care as well. not much of a wide coloration. but they are nice to have around :) i think they don't really have razor sharp teeth either (am not sure)
green florida snakes
i think they get a bit bigger than garter's, but they have a beautiful green, and a unique face. good beginner. they also have a nice yellow on them to. also we haven't had one for a while, and they don't live as long as pythons or anything, i think it was 4 years. am not sure with the colorations. but we fed ours pinkies (new born mice).
so i wouldn't get a king snake as a first snake.
green Florida snake: