Things you don't have to do on your website
While giving support about web development, it's surprising how many times you encounter with questions about how to do some stuff that I completly advise against. Most of us find this kind of things disgusting, but there is people who still does it and people who want to do it! So, please, don't do the next things on your website:
Adding background music to your site
I shouldn't have to explain this one. After the frames, this is the worse thing you can do to your website. Is annoying and when browsing several sites, it's impossible to know from where comes the music. Slows down the load of your page, due to the weight of the file, and if it's a light file, probably will be of a low quality.
Opening popups after X time
It's becoming quite common to open a popup that blocks the page after a few seconds to ask for login / Like on Facebook / Subscription to a newsletter... Please, don't do this. If I find interesting your content, I will promote it or I will subscribe to your newsletter. It's more important to have interesting content than doing this.
Sign up only with Facebook or other services
By doing this, you are limiting the amount of people who will become part of your site. There are countries where they can't access Facebook, there is people who don't want to share their private information and there is people who don't use Facebook. So, respect them!
Limit comments to users from a service
It's nice to externalize responsabilities to third party services: move comments to Facebook or Disquss... That's ok, but please, allow anonymous people to comment to. Don't force them to register in new services as a lot of people don't want to do it.