Pick two opposite words and combine them in a fun way. Here are two examples: Solid and hollow that are drawn like a solid object with the word hollow being the holes in the 3D letters. The second example is made with those little melting beads kids play with which spells true and false.
Good design, much like anything, starts with understanding the basics. Applying the following design principles will help you avoid design disasters and allow you to communicate your key theme. You'll find that it's rare to see only one principle being used at a time as they all work in conjunction with each other.