michael, i'm not really much of a pro dp, but i'd like to offer some general advice based on my (and others i've known) experiences...
no matter what the project, no matter what you're getting paid, no matter what the budget, do your best to make your final work look as good as possible. that's the only consistent way for a green creative professional (regardless of your specific profession) to get to where they wanna be, faster. i know that may sound totally obvious, but i've been out of school for seven years now and there is a huge difference in the careers of people who really live by this credo, versus those who reserve "giving it their all" for projects that they feel "deserve it". this'll also obviously help you build an impressive reel quicker, too.
even if you're dp on a short that is stupid and you know is gonna go nowhere... make it look as good as you can. someone's gonna see it and notice that the cinematography is particularly good and they're gonna make note of your name. if this happens in multitudes, then eventually it'll catch up with you. i guess there's a rough mathematical formula of x(quality of your work) + y(how many eyeballs end up seeing your work) = likelihood of becoming a working dp.
other stuff based on my limited experience:
1) if you wanna shoot music videos, then find the biggest band on the best label that you actually can get access to. get the best, most innovative director you know to approach them with you with a great pitch. shoot the video (undoubtedly for no/little pay) and make it look as awesome as possible, and make sure the video as a whole turns out awesome. if the band's big enough, then you have an instant audience for your work. if the video turned out good enough, and if the label's healthy enough, they'll ask you guys to do another video for the artist, or for another artist on their label. or get in contact with other labels that are on the same scale and namedrop your first video and ask if they're looking for pitches for any of their artists. blah blah blah, you get the point. the theory is that you gradually bag bigger and bigger labels & artists, and in turn your invoices have more zeros in them. though this model is more clear-cut for directors, and i'm not sure how strongly it applies to dps (though there are a lot of dual director/dps in the music video world).
2) find out which director major in your school has the richest family. court him/her and start shooting his projects.
3) build a time machine and find out which director major is going to get a three picture deal. court him/her and start shooting his/her projects and hang on to him/her like a leech dipped in superglue.
seriously though, because of digital, things seemed to have gotten really messy in terms of how to go about being a working dp. but i really can't reinterate the "give it your all" thing. this is especially important when you consider that when you get in your late twenties/early thirties, your energy level will be a fraction of what it is now.
hope this helps,
jaan