I’m only a senior myself, but I agree that getting a job is definitely a good idea. Not only does it allow you to earn some money, it’s also a great thing to put on applications 
You also could start researching colleges that you’re interested in, and write a rough draft of your Common App essay/any supplements you will have to do- or at least start brainstorming some ideas for them! I did this last summer, and it definitely lowered my stress levels during the first few months of the school year.