When you start, and as you run your new online company, it's important to always do things in a legal and ethical way. Most of us know this instinctively and would do so anyway, we only mention it because in the world of online business sometimes there are fine lines when it comes to ethical standards.
For instance, inevitably as a web business owner you are going to receive an e-mail or see an ad that says something like "Send your e-mail message to 1,000,000 people for only $199!" Does that sounds too good to be true? Well it is.
Assuming they just don't take your $199 and run, your message will go out to 1,000,000 people who don't want it. It'll be spam and it's a bad business practice. If whoever hosts your web site gets a lot of spam complaints about your site, they'll just take your web site down. This is because if they get known as a spam server, ISP's and search engines will refuse them access to the Internet, thus shutting down their whole operation. It just isn't worth it to them to keep the business of someone who spams.
If you have a content / advertising based web site and use AdSense to generate revenue you'll also undoubtedly be tempted to click the ads yourself to generate more revenue or maybe even have friends and family click the ads. Don't do it!
First of all, the person whose ad you are clicking on is probably a lot like you. They have a dream of owning a web business and are doing the best they can to make it succeed. If you click on their ad without having any real interest, you are robbing them of their money and making it that much more likely that they won't succeed. They deserve the chance.
Also, Google has some of the smartest technology around (we expect Google to become sentient within the next few years:-) and they will more than likely discover what you are doing and boot you from the program forever. Given how much real potential there is using the program, that'll cost you a lot in the long run.
Finally, you're never really going to grow to be a successful business by clicking ads yourself and having other people do it as well. Maybe between you and others you can have 20-30 people clicking or something. Forget that. Spend that time legitimately growing your site and get 200 - 300 real people a day in there checking out your content, then 2,000 - 3,000, then 20,000 - 30,000. Once you reach that point, you'll be doing really well for yourself and you don't want to risk your shot at the big time for a few easy bucks in the beginning.
Okay, enough of that!