Hey, I thought I should post because I actually know about this kind of thing!
So, By making your target market so specific (Such as a Teens only website) you are cutting out a large amount of potential customers/clients/listeners.
This in turn would reduce revenue from GoogleAds etc, but at the same time it also decreases the hits your website will get. Word of mouth is the largest advertising method there is, you have to make sure people want to tell others of this fantastic new website.
But lets go back onto potential customers and your target market. When you are making a website you should consider the following but at the same time allow for some common sense (A website wont normally be built for 70-80 year olds)
1) Your website should appeal to everyone if it is not aimed at a specific market, this helps ensure that people dont think you are leaving them out.
2) Your content must be suitable for all ages if the target market you are aiming at holds the age group of 0-15 years. Parents dont exactly want their children looking at ****ographic images or at very rude jokes.
3) If you go with a radio site, Make sure your DJs play music that has a wide variety, also remember to make sure songs with vulgar or fowl lyrics (Such as a song with a lot of swearing or a song with many sexual references) are only be played after 9pm.
If you want your site to be popular, you have to advertise. When advertising make sure that you know where your ads will be placed (You dont want adverts aimed at older people on a teen forum)
Your website should be clean but at the same time have a unique style. It should appeal to your target market but at the same time should be accessable for everyone (WCAG are a good place to start)
So when making your website, ensure you know what target market your site is aiming itself at!
Sorry for it being a bit all over the place but I hoped I helped,
.:; Johno

