Definitely Twitter! But I would like to learn the secret behind using Stumble Upon. I've been Stumbled at least once and got an amazing amount of hit in one day but since then nothing really. I've tried but don't understand how to get people to Stumble your posts unless you beg them to.
You can link your Facebook page with Twitter so your every FB post goes on Twitter. Make life extremely easy. Also, check the http://ping.fm/ it's free and easy service that updates all your social networks at once.
I use lots of different methods, so I can't say which is the best as I think they all do different things
1) http://www.twitter.com/jodymal I use when I am hanging out....take a little bit of a writing break...I always respond back to people who leave and @ reply to make conversation. Great tip for you as I have over 17,000 followers
2) since my new site (less than 2mths old) I've added a FB Fanpage http://facebook.dj/homepartyplan/ it's only 2 weeks old or so...but have over 45 fans already the great thing with this is....when you BLOG it gets automatically added and shows up in your followers streams....and if they 'like' it....hundreds more see it
3) NetworkedBlogs on FB is also a Great idea! just installed it as well! http://networkedblogs.com/followblog.php?name=home_party_plan Even though I have just a couple of 'followers' when I do a post I get tonnes of people reading it.....KeyWord Rich is the key
So between these three.....lots of new faces!
Plus, I will mention one that you don't have up top!
Technorati This is ESSENTIAL if you are a blogger!
Feel free to ask me any questions you may have....love to SHARE!