What to do with this infested yard?

So my boyfriend purchased a house in October and I was all excited because even though the yard is small I would be able to plant a garden and some trees. Now I am not fond of worms but I can deal with them, but I really hate snakes. We found one in the basement about a week or two ago. I pretty much had a panic attack, but my bf convinced me that it was just a fluke since we live in a city and near the beach. So I relatively go over it. So I noticed while trying to clean up the yard that there are a lot of snails and lots of dead ones too. Odd, but okay. So now I'm digging up some areas that were left neglected planning on putting some mulch and shrubs, I'm digging and raking then all of a sudden I see two snakes in the dirt!!! I'm freaked out. How much more crap could possibly be in this yard!!! I've never had this problem before and I've lived in two other places!!! I just purchased wood for a raised bed planter, and I am petrified at what I am going to find in that yard! And 75% of it is concrete, go figure.