When developing applications for Facebook there are a few pitfall that every developer should know about:

Facebook

• is not Reliable
• is very Restrictive
• documentation is all over the place
• has quite a few bugs
• fixes bugs regularly and also make more bugs at the cost of fixing one

After reading that you might wonder why should I develop for Facebook well:

Facebook

• is one of the most popular Social Network sites out there
• gives you a audience for free
• allows you to make money and have fun
• provides API access for multiple Scripting Languages
• now have alot of developers creating tutorials to make development easier
• does not require you to learn anything too new from what you already know about HTML
• makes sure you don't need to learn any kind of programming to make a simple tab app
• has a very nice test suite

Before creating any application for Facebook it is better to have it thought out and some research being done as to what you need to do, some of the work that I have done did not require me using any scripting language to do it. You can use a Simple Facebook application which is called Static FBML to get easy tasks done.