>>1
It's not possible to eradicate vandalism, but it can be reduced with three methods:
1. Good moderation
2. Good moderation
3. Good moderation
Okay, but seriously, people who don't want to moderate a community should not think about running a community.
Other tactics:
1. Limiting posting rate can be very effective but has to be fine-tuned very, very carefully. Cool downs slow down troll posts, but they also slow down quality posts.
2. Trolls feed off of reactionary energy. It's important not to feed into their drive. Get them bored.
3. There should be at least a little vetting process to enter the community, but it shouldn't be too rigorous, in which case potential quality users might be driven away due to apparent effort.
4. Commitment and good reputation in the community should be incentivized and rewarded.
Like you suggested, it's very useful to combine tactics.