I have an advice for you. When I was playing Beta in single, I used to getting advantage of the environment. So, build walls, under a mountain. So, you have the maountain for the creepers, and as a wall. Then, you make it in front of the mountain to have advantage, and then you modify the internal.
You can make also traps, under the wall with broken blocks, and some blocks in wide, to leave them open, in order to hit behind the walls..
OMG! When will I get my Beta?