When it comes to blogging, content drives traffic, leading to profits.  If profits are in your list of motives, then your main goal each day is to write and promote what you have published.  In some cases, simply writing content won’t help your blog expand and reach new levels.

One of the main things to remember is that content never comes free.  If you receive most of your traffic from Google, you obviously put time into creating links to your site or added keywords and content-rich information to your site.  On the other hand, if a large percentage of your traffic is direct, then you worked on branding, had content, and reached out to other “high profile” bloggers to help spread word about your site.  In all these cases, time was the leading method for growing your site.

Alternatives to taking this approach and promoting a select number of posts can help gain more for less time, and when time is valued higher than money for many people, spending cash to promote posts can be a good idea.

1. Use traffic-generating widgets (Entrecard, Spottt, etc.) and use individual posts instead of your main blog URL in order to potentially gain more comments.
2. Advertise on other bloggers’ blogs using a link back to the post, which may lead to a lower bounce rate - people who click on the ad may want to see a list of recent posts, so they travel to your homepage.  Disadvantage: Higher cost and lower return if visitors don’t find the post interesting, plus the ad may be running for a full month instead of a shorter period. 
3. Purchase ads through AdSense, especially for posts that can lead to a good return (e.g. reviews of products, services) that wouldn’t normally receive a lot of traffic.  
4. Uniqueness equals traffic and new subscribers.  Applying this principle to your posts, try something different, whether it simply be in the style that you write or the graphics you use when trying to get your point across.  When I look for qualities in blogs worth subscribing to, one of the main things I look at is the design of the site, number/quality/uniqueness of posts, and what character the author puts into his or her site.  
5. Push your posts to other web services including Twitter, Digg, StumbleUpon, FriendFeed… and the list goes on.  The main point is to involve people who “follow” you, to let them know about your recent post.