Richard Weaver defined conservatism as "That paradigm of essences towards which the phenomenology of the universe is in continuing approximation." (Sounds very Bill Buckley, doesn't it?)
Libertarianism is not quite so simple, but the basic idea is to maximize individual liberty. There's a lot of variation among libertarians. I'm one of the more conervative libertarians myself, and I'm not always sure of the difference between me and a Goldwater Republican (if I'm not the only one left) but radical anarcho-capitalists are libertarians too, though those don't generally vote or participate in the Libertarian Party (or any party).
Really, the only things that all libertarians have in common is that we're for as much individual liberty as feasible, though of course our assessments of how much that is vary widely, and that we're pro-free market capitalism (because those who aren't, even if they're for minimal or no government, almost never call themselves libertarians).
Advocates for Self-Government is a great site to learn more.