If you’re a student, you’re probably getting close to the end of a long end-of-semester checklist. However, Debbie Downer is here with some bad news for you: we have one more item that should be added to that list. Before you leave for the summer, you should consider which professors you’ll be asking for letters of recommendation.

We’ve written about letters of recommendation before, so you may already know that the best letter is one written by someone who knows you well and can write convincingly about your academic skills. Some choices for recommenders are easy: for instance, it would absolutely be preferable to ask the TA who knows you well rather than the professor of a big lecture who doesn’t even know your name. But what if you’re trying to decide among several equally good options?

One thing to keep in mind is that the best applications have complementary letters of recommendation, meaning letters that fit well into the overall big picture of your application without being repetitive. Most professors are receptive to suggestions about what topics to discuss in the letters they write, so think about what skills you exhibited in each class that your recommenders might be able to discuss. If you have a good relationship with several professors who could speak to your writing skills, but only one of them can speak to your research skills, you’d probably want one of your letters to come from the latter.

You might also wonder whether the professor’s area of expertise matters in terms of requesting letters. The short answer to that question is: not really. Law schools don’t expect you to begin school with prior knowledge of the law, so whether a letter comes from a Constitutional Law or from a Biology professor is less important than the content of the letter.

With that said, how well the letter is written could make a difference. For instance, I’ve spoken to a pre-law student who wanted to have a foreign professor write her letter but was concerned about whether any grammatical errors in the letter would reflect poorly on her application. Of course, the letter writer’s proficiency with the written word won’t be viewed as a reflection on your own proficiency. But the fact is that a more polished and easy-to-read letter will have a more professional tone. That shouldn’t dissuade you from asking for a letter from someone who isn’t the next Steinbeck, but again, if you’re deciding between several professors, it’s something to keep in mind.

Letters of recommendation are a great opportunity to have someone else brag about you, so you’ll want to take full advantage. You probably won’t want to bug your professors while they’re still in the midst of wrapping up their own end-of-semester work, but the summer is a great time to ask for letters of recommendation, so start planning who you’ll be asking now.