In case you are applying for an RA ship, here is my list of preferences:

1. I have had you in one of my classes and you performed great.

2. you *understand* undergraduate/beginning graduate mathematics
(linear algebra, basic numerical techniques) I will also look
for your grades in data structures/algorithms theory.
    Tell me about your favourite equations solver.

3. you know how to write code or can learn it fast.
    Tell me what you think about templates and the polyhedral 
    data structure in CGAL.

I typically support outstanding students for a PhD
(as opposed to programmers for an implementation).
I am always impressed by someone who asks intelligent questions.