Lens hoods - As I said, photography is all about controlling light. Too little light results in blurry, muddy photos. Too much of it can also cause problems. You particularly want to avoid stray light that can result in ugly lens flares. Lens flare shows up as washed-out circles on your photos. You can't fix them in editing.
A lens hood helps you block stray light. Using one is the best way to avoid lens flare. Unfortunately, not all lenses come with lens hoods. You can spend a pretty penny on one, and it will only work with one particular lens. Try this site instead. It will help you create lens hoods for free!
Tineye - The Internet makes it easy to share photos. It also makes it easy for people to "borrow" your photos. You might not be getting credit for your work. Tineye lets you run online searches for your photos. It uses powerful comparison technology to match images. You can find other instances of your photo online.
Tineye works as an online service. However, it also has a Firefox add-on. This lets you right-click any image in the browser and search for it.