It's recommended not to overload during a project. Project work, in particular, can suffer when overloading since it typically doesn't have the same "due dates" as might a class (e.g., Homework 1 due Friday). Also, it might be tempting to overload to "catch up" after previously NR-ing some courses. This is generally not a good idea since you might have fallen behind because you can't (yet) keep up with the load. Trying to overload to catch up may put you further behind! So, first figure out how to handle a typical, and even busy, term before trying to overload.
But if you do want/need to overload, below is some advice:
Start earlier. By now, you have figured out the (fast) pacing of terms versus semesters. When you overload, you need to start assignments even earlier than you might since there are more moving pieces (classes and their assignments) that might cause conflicts.
Seek help early. The extra load, coupled with the fast pace of terms, makes it more critical not to get stuck or behind in any one class. If you find yourself in such a position, seek help from the TAs or SAs or ARC or the instructors for your classes sooner than you otherwise might.
Be prepared to bail. Of course, you are going into the term expecting to succeed in all four courses. But if it turns out that you cannot manage the load, it is better to intentionally drop one course (which will be an NR and won't show up on your record) than it is to unintentionally NR 2 or more classes. This holds for low grades, too, or learning less than you otherwise could.