Obtaining strong letters of recommendation, for me, is a really vexed thing to do. Here’s some pointers that I’ve been working with for a few—hopefully you find them helpful:
*Only ask people to write your letters if: (1) they know you in at least a classroom capacity, but ideally they also have a sense for a range of skills you possess (e.g. teaching, researching, communicating in class, etc.). (2) you are confident that they can write you a strong letter.
* Be strategic in who you will ask for letters and how you will ask for them. Anyone can write you a letter of recommendation; not everyone will write you a glowing one. Not only do you want a stellar letter, you also want a letter that will come from a person who is well-positioned to evaluate and speak to your strengths. On this note: ALWAYS ask for strong letters; a mediocre letter will only hurt your application and you don’t want that—and, in all likelihood, neither does your letter-writer.
* Communicate with your letter-writers WELL in advance of deadlines. I typically give at least one month whenever I can—though I have had to ask faculty to write letters for me in a pinch. As soon as I find a grant (job, fellowship, etc.) that I want to apply for I put it in my calendar and set a few reminders to myself about sending out emails soliciting letters well in advance.
* If you’re asking someone to write a letter and they have never written one for you before be sure to ask them what all they might find useful in writing their letter.
* Regardless of whether this is their first letter for you, you should do your best to get them a copy of the materials (even if they are rough) that you will use in the application they are writing about. I often also send a copy of my CV and, as appropriate, an abstract of the project I’m proposing in the grant (in addition to the complete materials).
* Be super polite!
* If, for any reason, someone is not able to write a letter for you—whether because you haven’t done well working with them, they’re swamped, or they have a conflict of interests—don’t freak out! It isn’t the end of the world!
* Assume you have a right to letter writer’s time, energy, or their good graces. It is always an honor to have someone write a strong letter on your behalf, and I’ve found that the more I share with them about how much it means to me, the less faculty hesitate to support me.
* Ask someone to write a letter for you that is due two days later. That’s never good form!
* Be too shy: if you need a really strong letter then you have to be up front about it. Most people will write a letter if asked to; that doesn’t mean it will be what you want.