(1)Remember, this is business. Appear professional.
If you were looking to hire a realtor and could choose between one who arrived at appointments in old-school basketball skiviies and a sweat band, or one in a slick grey suit with sassy red heels, I'll bet you twenty bucks I know who you'd choose.
(2) For the most part, you'll find your advertisers. They won't find you.
The sooner you see yourself as a salesperson, the sooner you'll start making bucks from your blog.
As you look for advertisers, look for companies that are equal in size to your reader following. If your blog is seeing two hundred hits per day, a major corporation is highly unlikely to be interested in sponsoring you. However, that doesn't mean other, smaller companies aren't looking to increase their audience and profits.