How do -you- go about getting attendees to a convention? I have experience going to local anime-themed events at local businesses, telling people at other conventions I go to, using convention websites to spread the word as well. There are probably tons of options.
Number one best way to get more attendees at your con is to attend other cons. Throw interesting & fun parties. High cost isn't 100% necessary - be creative. Heck - throw your party at a time when others aren't. Mid afternoon Ice Cream social that only runs a couple hours. Make arrangements ahead of time & take over the consuite for a couple hours. But serving rice & roman just like the con suite won't get you noticed & remembered. Be pleasant & encouraging. Help out at the con you are attending & get to know their staff. This makes them want to come to your con & help you out too.
Attending cons: definitely big. It's one of the ways to get the habitual cosplayers and conattendees to come to a con that's somewhere in the region - and these are often the people that really really support cons. It's important to see it's not the only thing, though, since many first-year cons have a harder time attracting attendees that aren't local.