How to write a recommendation letter for a student you don't quite remember

I really DO enjoy being asked to write letters of recommendation, but every once in a while, as happened this past week, the situation described in the title of this post arises. So, I thought I'd pass along a few pearls of wisdom regarding said situation:

1) Think, before agreeing, at least to ask the question, "Now, just when exactly were you my student?" At least that.
2) Incubate the letter's content (read: put off writing it in favor of more pressing and/or more enjoyable matters).
3) Repeat step #2
4) Repeat step #3
5) Along about the day before/the day that the letter MUST be written (these things are for silly, inconsequential things like applications for scholarships, for schools, for jobs, etc., and they always seem to have deadlines by which they MUST be written), tell yourself, "I've GOT to write this letter!!"
6) Repeat step #2
7) Repeat step #6
8) Kick yourself in the ass and say, "Dammit, I've GOT to write this thing!"
9) Auger the ol' grey matter (this is NOT to be confused with incubation (see step #2)).
9a) In case the student has a gender-neutral first name, at least get fixed in your mind the student's gender so as to avoid the difficulty of having to write sentences that both avoid the use of 3rd-person pronouns and yet sound like they've not been written by a machine. By this point, time will most definitely be of the essence.
10) Strike a positive tone: "It is my pleasure to write in support of _____________'s application to receive the Whatchamaycallit Award." You may not quite remember this student, but that's no reason not to strike the pose of enjoying the task of making up something that is, in Faulkner's inimitable phrase, "true enough."
11) Indicate, without being too precise (since you can't quite remember, remember), that the student was once in your class.
12) Recall that NO student applying for these awards is EVER unworthy of it--even students you can't quite remember. It's a priori. So, say that the student deserves said award, and enjoy saying so (see step #10).
12a.) Because every student applying for an award is, ipso facto, a Good Student, when writing letters of recommendation for students you don't quite remember, that fact is an enormous blessing: just write down the sort of stuff that Good Students in your classes do. The body of the letter writes itself.
13) Make yourself available to the reader(s) of the letter if s/he/they might require further information on this candidate.
13a) Fervently hope s/he/they do not.