Some things I've learned along the way about getting and being married, some of them first hand, others by observation of close friends.

Before Marriage:

First thing: Make no commitment until you've both been out of school and living in the 'real world' for at least a year. People can seem to change tremendously in that year as they deal with everyday stresses and situations they've not necessarily faced before. Values, priorities and behaviours will show up that have never had a chance to reveal themselves until 'real life' hit. Until that happens, you don't know what you're getting into.
'Husband' and 'Wife' are roles we've grown up with particular ideas about and, when we become one we tend to modify our behaviour to fit our understanding of the role and expect our mate to do the same. The trouble is that each of us has a different image that is conjured when we hear the word 'husband' or the word 'wife'.

Before you get married, you two need to examine your own and the other's preconceptions about what it is to be a husband and to be a wife, to compare and contrast them and, as much as possible, reconcile them.
If there's a hole in the relationship (love, respect, sex, caring...) don't expect getting married to fix it. Work it out before you make any other plans

Any Time, Any Relationship:

Don't assume. If you don't know for sure, ask. If you can't ask, there's a communication problem OR it's something you don't need/want to know. Forget it. Really Forget it. If you can't forget it, y'gotta address the communication problem so you can ask.
Everyone has goofy little things that make them feel cared for, figure out what yours are and find out what your mate's are, talk about them and make them part of your vocabulary for dealing with each other.
Basic rules for life:
1. Don't be stupid
2. Don't be a jerk
3. Don't immediately assume that someone's breaking rules 1 or 2
4. Don't immediately assume that what's happening is being done to you
(if you think about it, each is really an elaboration on the one before)
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