here are a couple of things that i commonly use in my breadboard projects
Step 1: Use staples as small jumpers
i found that staples fit perfectly into the holes of the breadboard, you can even fit two in the same hole.
Step 2: Fitting multi strand wires
if you dont have many single strand wires (like me) you can use multi strand wires without them crumbling by soldering them, first twist them up as tight as you can get it, second, melt a small amount of solder int the strands and it will be solid like multi strand wires. this might not always work eg. you add to much solder, your wires are to big, there are two ways around this, one cut some of the strands off, two proceed to the next step.
Step 3: Making bigger holes
if you are building something that has leads bigger than the holes in your breadboard wou can widen them with a jeweler's screwdriver, it works best with flathead. just poke it in the you want to widen and twist it back and forthr. be careful, if you go to far you could ruin the point, you should feel the difference when it hits the metal.
*if you ruin your breadboard im not taking the blame for it*