I think to start a good marriage, you have to keep a mindset of maintaining a good marriage. It's a long-term and ever-evolving goal, so have the basic priorities in place to maintain it when you begin. I've never been married, so I wouldn't quite know. To me it seems like a relationship, but with legal papers.
So with that in mind, I think about what it takes to start and maintain a good relationship. Don't act like somebody else from the start, where then after you get past a few bases, you do a complete 180 and scare the crap out of your potential mate.
Stay honest, be yourself, and make sure all your quirks are known when things become serious. Be aware of all your mate's quirks. Marriage should be when you know you can accept and love all the bad and the good.
Oh, I'd suggest living with the potential spouse for a few years before marriage to see if I could handle all his living habits. A good start to a marriage can be spontaneous (some marriages have been spontaneous at the start and survived many years - very rare), but I would hope afterwards there was some realization to wanting to maintain a powerful relationship with the love of your life - for the rest of your life.
Edited to add: Oh, and a few words for a good start to a marriage.
1) Openness and transparency.
2) Boundaries.
3) Being on the same page on what marriage and love means.
4) Positive communication and negotiations.
5) Trust.