Yesterday, Eric Shupps posted a great article for getting started with SharePoint development. If you are just getting started with development for SharePoint, I highly suggest taking a few minutes to read his article.
Also, here are some good resources for you to consider when starting to develop for SharePoint.
- Best Practices: Common Coding Issues When Using the SharePoint Object Model
- Checklist for Creating SharePoint Web Parts
- Best Practices: Using Disposable Windows SharePoint Services Objects