So you want to place advertisements on your site? Or do you want to increase traffic? Regardless, you need to have a good amount of traffic before you should consider placing ads (unless you mind getting your $100 check annually).
I'll explain the whole advertising bit:
I suggest Google Adsense over Yahoo. You may also try Adbrite which provides more graphical advertisements than Google.
The best, and most money making, advertisement is the wide banner ad that you place at the top of the page (dimensions are like 748x40 I think). You get more money (in theory) for big banner ads that are at the top of the page because that is one of the first things people will see when they access your site.
You are paid on the amount of pageviews that advertisement gets and also how many clicks it gets. Now, don't think that the more clicks means the more money. Pageviews are just as important as clicks.
To answer your question: Yes, Google Adsense does work. I'm getting my next check in a couple of days for $100.
Question 2: Are you asking for a forum script or a forum which you would be best to advertise in? Either way, I suggest Invision Power Board or vBulletin for a forum. If you really don't want to pay for a license, get phpbb, MyBB, or another PHP forum script.
If you would like to advertise your site in a forum, you have to find the target audience of your site's content and provide links to your site and explain what it is.
Question 3: Requirements for a successful site:
1. Content that people want. Just having any content doesn't necessarily mean that your site is going to be successful. You need to have content that a big group of people can use.
2. An interactive interface. Most people, depending on the genre of your site, want to be part of the community in the site. Since you mentioned a forum, I am guessing you want to have a community. So setting up a PM system, profiles, and a forum will help users be active within your site.
3. Nice design. Let's face it: People like attractive things. If your site is bland and plain, no one is going to go to it because it's not "eye candy", so to speak. Get a good design that is attractive, clean, neat, and organized. No one likes cluttered text and squished tables.
4. Let people know. Your site is not going to get up off its feet without some spreading of the word. Google is not going to help you out. Sites with less traffic are at the end of the search listings. You need to spread the word to friends and in forums or communities which share the same interests that your site provides. Say you've made a Halo fansite. Go to other Halo forums and spread the word of your site.
That's all I can think of for now but I hope that helps you out!
Good luck!
