In the shop I use a lot of random small pieces of wood and paper to assist me with my work. I hoard all small piece of scrap wood and keep them in a zip lock bag. I find myself reaching for that bag of scraps to use them as shims. I use them to shim up my shoulder plane to keep it cutting parallel on a rabbet or even as a pad for my C clamps. The most helpful shim in my shop is the simple Post-it notes. These guys are great because they have a sticky end. I use them frequently on my shooting board to offer up a piece of timber "square" to the plane. This is a trick I picked up from David Charlesworth in his Shooting DVD. You can find a variety of uses for Post-It notes just give them a try.
Setting the projection of a hand plane iron can be difficult. I use a curved iron in most of my bench planes and I want the curve as centered as possible. Most authors suggest using a white piece of paper as a background to site against as you witness the iron emerging from the sole of the plane. I find this difficult to see. I will use this method to set the gross projection and balance, but will fine tune the setting with shims. First, retract the blade into the body of the plane. Second, slowly advance the iron while sliding the shim back and forth over the mouth. Soon you will see and or hear that the iron is cutting the shim. By noting where the shim is being cut on the width of the blade you can compare it to the opposite side of the iron to see if your iron is balanced in the plane. I use small wooden shims, about 1-1/2” x 2” works the best. I use both long grain and end grain shims. I prefer the end grain shims because you can hear when they are cutting. This makes it easier to set the plane because I can hear it cutting rather that looking on the inside of the mouth to see if it is cutting. Long grain shims will get a fiber mark to illustrate the direction of cut. With the end grain shims this is of no concern. They can be used in any direction. I will try to make these shims from a close grained hardwood like maple. To make the end grain shims just take a piece of timber about 1-1/2 thick and 2” to 3” wide and slice a 1/8” to 3/16” off the end. Long grain shims can be cut out of stock but usually you can find some off cuts lying around. 
Paste wax can help make your next projects parts fit perfectly. When fitting the lid on the Herwiggy humidor I used a thin coat of paste wax on the lid. When the lid was closed, tight areas would show up on the lid slip. I would locate these areas and take gossamer shavings to remove the material for a perfect fit. The same rules apply when fitting drawers in the traditional manner used by Alan Peters. Once the drawer is build, but before the bottom is slide in wax the drawer opening in the carcass. The wax on the inner surfaces of the carcass opening will burnish the high spots and allow the craftsman to achieve a perfect fit. 
Few tools make the cut when it comes to what I carry around in my woodworking apron. You will find in my apron a square, tape line, marking knife, pencils, sharpies, a pen, safety glasses, wooden shims for setting planes and a rectangular block of wax. In my work a block of wax is just as essential as a marking knife or a square. I find myself reaching for wax to ease multiple areas of my work. The usefulness of wax is not just limited to a hand tool workshop it has many uses with power tools as well. You can pick up a block of wax at any grocery store that sells canning supplies. Look for canning wax or paraffin wax. There are other types of waxes available, but they tend to be hard to find and more expensive than paraffin. Under $5.00 will buy you enough wax to last many work years in the shop. Here are just a couple of uses for wax in the shop.
When cutting wood with a hand saw wax can make the saw glide through the cut and slice the wood sweetly. Large panel saws always get a light squiggle a couple inches above the tooth line before they touch the timber. Dovetail saws and other backsaws will also benefit greatly and let you focus on sawing to the line not excessively forcing the saw. If you are tired of always breaking fret saw blades because of them binding in the cut running the block of wax on the back of the blade allowing it to cut into the wax will coat both sides of the blade and will turn your blades into marathon runners. This will work great in coping saws, power jigsaws and scroll saws. 
If you have ever snapped off a brass screw when installing that last piece of hardware in a project you know how frustrating this can be. Second only to drilling a properly sized pilot hole and pre-threading, wax can facilitate a smooth entry for any screw and prevent breaking. Wax is superior to soap in this application because soap can hold moisture and cause the screw to rust.
Recently while working on my bench the round brass bench dogs became very difficult to push up above the bench. A light coat of wax on the spring and far side of the dog solved the problem quickly.
