II. Paid Traffic.

Paying for traffic assumes that your site is supposed to bring some revenue back. Otherwise it's pointless to spend money for getting visitors. Actually, the idea is that you get more money back than you've spent for traffic.

1. Buying banner impressions. In other words, you pay other web sites to show your banner. Unfortunately, this is not a very good idea. The reason is that “impression” does not mean a visitor. Impression means how many times your banner is shown, but clicks are what really counts. Usually, the impression/click ratio is about 1000/3-4.

2. Buying guaranteed traffic. There are lot's of traffic brokers who sell “guaranteed” traffic. Sounds good, but usually the traffic is very low quality, because they buy wholesale from the Surf Exchanges. Of course, you may try it. Sometimes it's very cheap. Personally I've used a site located at http://www.immensehits.com . They sell 10000 hits for $7.95. Even if it doesn't work for your, it won't be such a great loss.

3. Buying text links. Well, this one might turn to be very good because people tend to click text links much more often than banners. Of course, you have to make a good research where to buy text links and negotiate the conditions. This is something like the free link exchanges, but when you pay for it, you may feel free to require a better placement for your link.

4. Bidding for keywords. This is one of the most popular options at the present moment. A lot of search engines, called “pay per click” search engines (PPC SE) let you bid for getting in the top results for certain keywords. You create an account at the SE and send some amount of money. After that you create a listing for your site with title and description. At the end you choose keywords for which you want to rank high in the search results of the PPC SE. You assign a certain amount of money you are willing to spend for a click on your link when your site appears in the search results for that particular keyword. If your site gets the click, that certain amount (usually a couple of cents) is deducted from your account.

Pay per click campaigns might get very expensive, but the quality of the traffic is much better than from the other mentioned options. Of course, your site has to be tuned in order to return more money than you've invested in the advertising campaign.

Some of the popular Pay Per Click Search Engines are:

http://www.overture.com – very hard to get accepted.
http://www.findwhat.com
http://www.kanoodle.com
http://www.7search.com

and, of course:

http://adwords.google.com

I hope that this info has been useful to you. I'll edit these tips every time I come across something new that works.