Pay-Per-Click is one of the options you can choose from
The downside is that pay-per-click is essentially a bidding war. A higher bid than yours will lower your position on search engine results. This means that you will have to raise your bid to regain your position - which can obviously become quite expensive, especially if you are bidding on a popular keyword. Needless to say this will quickly gobble up your advertising budget.

In order to determine if pay-per-click is a cost effective form of marketing for your business, you must do some computing to figure out how much each visitor to your site is worth. You can compute this value by dividing the profit your website made over a given period of time by the total number of visitors during that period. The basic formula is profits divided by visitors. For example, if your business made $5,000 in profits and there were 2,5000 hits, in theory each visitor would be worth 50cents. However at fifty cents per visitor your business will just break even. Of course you need to show a profit, not just cover costs. To that end you need to aim at a figure less than 50 cents per click.

More about pay per click.
Because machines surf more than people you might be charged for their clicks. In addition,
daily management monitoring time is required, while it's fairly easy it can be time consuming. Also statistics indicate users have a tendency to skip over sponsor links/ads as artificial search results. As mentioned before, bidding wars drive up cost making Per-click costs on popular terms very expensive. You may find popular terms to be so expensive they are cost prohibitive.

In general Pay-per-click programs pay less than affiliate programs because you are trading higher commission rates for a higher probability of earning income since your visitors don't have to purchase they only need to click. However, because of it's general nature, if you have a website with a narrow focus/narrow targeted audience pay-per click may not be your best choice. You should also know, certain pay per click programs cap the click-through ratio, claiming this is an anti-fraud protection measure, other pay-per-click programs cap the payout amount you can receive based on the ratio of the amount of ads displayed by you against the number of users clicking through those ads. When you have a highly relevant, targeted site this practice can negatively impact your potential income.

Before signing up for any Pay-per click program or adding banners to your website consider the following factors:

1) How do they count click-through?
2) What do they pay-what is their payment history?
3) What are their payment terms?
4) What are their terms and conditions?
5) What other tools or features do they give you?
6) What is the quality of their advertisers?

Before you commit to any agreement carefully read the entire document. You can bet if there are restrictions, they will be discreetly hidden among some elaborate legal terms. Caveat emptor!