There's a few options that you can use in tandem.
Blog is easy, goes right with your core website. The tricky part to the blog is if it is not something you are already doing, do not try to do it "just to do it" - update once month at least, but don't spam out updates just to fill content. Meaningful content is more useful than just updating all the time.
Forums, large blogs, etc. If you are already part of appropriate gaming (or related - say, fantasy, or sci-fi, or whatever) communities, it's pretty easy to find a promotions or "other" folder and put up an announcement and link your game in your tagline.
If you are not, then you should participate in a real way - that is, don't show up, drop promotion and leave. Go to sites you'd actually like to drop in on, at least once a month and participate in MORE than promoting your game.
rpg.net is a pretty good site in this regard - they have an ongoing thread series for crowdfunding and kickstarters, so that's a nice extra.
If there's any gaming podcasts you're into, see if you can get a shoutout or guest star on them. Maybe give them a free copy of the game, etc.
Demo Play Video
Short 3-10 minute videos of some demos of key points of play - how the rules work, neat bits, and share them.