The Manual of Chess Combinations Chess School 1A and 1B are excellent. You can click on my last blog post here, I reviewed the software version of it recently. With that said I believe software is a bit better because you can go through problems more quickly. You just have to train yourself to not cheat. By that I mean that you don't see the followup moves but you make the first one and wait for the program's response, obviously it can be very detremental to your rating if you try to do that in a real game! With a little bit of discipline I was able to avoid this.
Of course you can always just use the tactics trainer here. I don't use it but many find it useful.
Might I also suggest a basic tactics book? Chess Tactics by Paul Littlewood is a good place to start and Chess Tactics for the Tournament Player is excellent, I've read it three times and always get more out of it. I will say though that I was rated a bit higher than you the first time I read it and found it to be a bit rough, I got more out of it when I was 1300 (OTB) and again when I was 1500.
Hope this helps.
I'm looking for a chess puzzle book and am not sure where to begin with all of the choices out there. I am an adavanced beginner. Any suggestions? Thanks.