I'm relatively new to the piano and have only been playing for 6 months. I've got the major/minor arpeggios and some basic songs down. Does anyone have any good books or exercises they recommend to take my technique to the next level?
Welcome to Music: Practice and Theory Stack Exchange! I am happy to hear that you are learning to play the piano. It is a great instrument to learn. You can begin taking your technique to the next level by learning scales. There are quite a few of them and here are the major 4 scales you should learn. Learn them in all 12 keys.
To further train your fingers, there are a few books that you can choose from for upping your piano technique. A couple of books that I used for a few years are Hanon's "Virtuoso Pianist in 60 Exercises" or Czerny's "Progressive Studies". Both of these books get progressively difficult with each exercise, so make sure to master each exercise before moving on to the next one.
Once you have mastered that (after a couple of years), you can start thinking about learning Chopin Etudes. Those are my personal favorite and once you are able to learn those, they will take your technique to a phenomenal level.
I hope that helps! Let me know if you need further clarification!