Fighting Spam for a New Startup

Heya! For my site launch I'm pretty sure I need to be ready to fight spam, but I'm not sure how ready. At the very least I'll set up a basic spam filter, but I'm unsure if I should train it myself beforehand (by copy and pasting the 1000 Gmail spam emails I have in my inbox) or wait until site launch.

People will write text that other people see, so it's probable that some of it will be spam.

What do you all do? Is there a big database of spam to preconfigure spam filters?