And what issues are most important to you?
Balancing the budgets (inc. entitlements), illegal immigration, and foreign policy (both trade deals & the WoT). Those aren't in any order by priority; I can't really place one above the others. The WoD is also a big issue for me, as increasingly will be energy policy I suspect, but there isn't much to work with on the former (nearly all politicians toe the line) and the latter is more of an abstract concern. I'm very concerned about scientific progress and maintaining our technological edge as well, but the ways that politicians matter to that mostly fit into the issue areas I already listed above.
Oh, and education policy is very important to me as well, but perhaps just slightly below the big three I mentioned - mainly because I don't have crystal clear views on how that should get handled and also because it's primarily a state issue, or should be. It would be a non-issue to me on the presidential level if education weren't becoming a federalized sphere. That's the first criterion I use for governors, not nearly so much for presidents.