So, you want/need a knife? Here's a thread that may help. A knife is one of the most useful tools you can have. Different knives are suited to different tasks, so you'll probably have to buy a few.

First off, you need to buy a Swiss Army Knife (hereafter referred to as SAK). Doesn't really matter which one- have a look at several and pick the one you like the most. You can always buy another later.

Okay, now that you have your SAK, you can look at getting another knife. First, ask yourself what you'll be doing with your knife.

Now that you've answered that question I can tell you that most of the time you'll be cutting cardboard with it. That's not a bad thing- cardboard dulls an edge real fast, and is a great way to learn about sharpening and how long different steels with different treatments and blade shapes stay sharp.