[Kate*]

If you're interested in graduate school the two best things to do are consult your advisor and start your research early. A double major won't necessarily make you more competitive and your GPA is more important than your degree in some cases; For example, you can apply for a PhD. in psychology without a degree in psychology (though they do prefer one), you only need 18 hours of psych including 4 or 5 specific courses. The first thing I think of is that this is A LOT, I took 18 hours once and decided to never do it again for the sake of my sanity.

Unless a double major makes you competitive based on admission requirements, or the second subject is so interesting that you feel the extra work is worth it, you might want to scale back. If you take on so much that your GPA suffers, that may seal your fate regardless of the fact that you have two degrees. The classes you're taking matter more than how many you took at a time. Don't schedule yourself so strictly that if anything unforeseen happens, you've made things impossible.

Also, check multiple times to make sure that the classes you plan/need are offered when you've scheduled them; especially for summer and spring where there tend to be fewer options, some courses only taught in certain semesters and, my personal favorite, the one required course only taught one semester of alternating years (good luck coordinating that!) can throw a serious monkey wrench in your plans.