Layout tools: A marking knife, a compass, a square, and a tape.

The first thing that you really need to have for woodworking is a marking knife. It doesn't have to be fancy. A cheap way to get started is with an X-acto knife. You know, the little ones with replaceable blades. Maybe a utility knife if you prefer. What you will want to look for is a blade that has a single bevel. That means it is flat on one side of the edge. If you have a double bevel, it will tend to try to follow the grain of the wood instead of following a straight edge. Some have a spear point so you can mark toward you or away from you. That is nice too. A marking knife will give a much finer line than a pencil It will also be used to cut out a little sliver of wood to make it easy to start a saw cut or to pre-cut to keep the wood from splintering. More on that when we actually start talking about making stuff.  Do keep a pencil handy though, it is great to use one to highlight a knife line.A quick rub with a pencil will really make it stand out. We will come up with a better solution later.

A compass (a divider is a better term since you really don't want one that works with a pencil.)  is really useful for woodworking. It can mark out circles and arcs but it is also useful to compare two different widths and finding the center of things. Drafting supply stores or office supply stores will usually have one.

You also will want to get a square. I suggest a 12" combination square for a start. They generally come with a 90 degree angle, a 45 degree angle, a level, and a scribe hidden in the body. They can range from about $5 to several hundred dollars. Unless you have a reason for other work, the expensive ones will be much more than you need for woodworking. I have several in different sizes up to a 4' drywall square that is really useful for working with sheet goods. A steel blade is better because you are going to be running a steel knife along the edge. 

The last measuring item is a tape measure. It is really just a convenience as much of woodworking is done with relative units such as marking off of other work pieces.  Unless you are building a house or something, a 10'-12' tape is plenty long. Look for a wider blade on one so it will support itself better. If you are going to be working with metric measurements, don't mess with one of the combination tapes that has metric and English units. Get a fully metric tape and an English measure tape. The ones with combination units are awful because you can't use both sides of the tape with either unit.