In general, I vote by the following order:
1) What is good for me
2) What is good for the Jews
3) What is good for the nation
Usually, 1 and 2 line up very well. My stance on number 3 doesnt always match up 100% with 1 and 2. Also, I look at the issues that are extremely important to me vs what is just ideally important to me.
For example, I am pro-choice for first trimester abortions (I think partial birth abortions are horrific). One reason I am pro-choice is because halacha allows abortions in certain situations. Although I would never have an abortion barring extreme circumstance and rabbinic approval, I need to be able to choose abortion if my Rabbi tells me to.
Also (and I may be stoned here for saying this), I am pro gay marriage. Gay marriage is SECULAR – I had a Jewish wedding and a secular wedding. With gay marriage in place, they would be able to get health coverage from their partner and help prevent/treat more diseased people in the gay community. In addition, assuming monogamy amongst the gay community is the same as the rest of the population, you would also possibly prevent the spreading of diseases to more people. Not allowing gay marriage won’t stop people from being gay and allowing gay marriage DOES NOT mean that you approve, which I dont.
So while that is my stance on those two (relatively) controversial issues, I won’t vote based on them, because they dont really affect my life. There are more important issues, which is why I am voting for McCain/Palin.