I try to marry in the first year of the game.
I go for the following:
1. Faction of future intent to join or rule - partner may become a governor so good to know.
2. High traits: steward, charm, trade, tactics, leadership - charm because I'll leave them in a city for a few years where I want to use as a base to get my recruit levels up.
3. Armour and bow. For me, having good armour and a noble bow allows me to go without a party for a year or two - solo runs speed up your faction and character levelling up.
I usually end up marrying one of a small group of the same men or women (I play as either depending on my mood) where traits align with gear. But some gear I leave for down the track (I used to look for a glaive or rhomphalia, but I tend to go for a sledge hammer early game now). I'll marry off my brothers strategically to get more gear, a good horse, imperial armour or good trade skills (because they're all going to run caravans in the early game - brothers and all) - unless there's someone left on the shelf with really high medicine or engineering, I might take them into my party.
I don't care about their fighting skills. They're all going to end up alongside the archers with a crossbow anyway.
What's this 'looks' thing you talk about?