Preheating or warming the glassware you pour into helps. Keep an eye on the items you embed or add to the gel. Often they will produce bubbles as well as some wicks. We will discuss embedding and wicks later. When working with the gels, try to use metal rather than wood spoons.
Wooden objects tend to cause bubbles.
Pour gently down the side or from a close distance, much like pouring a beer to avoid getting a big head of suds. As your gel is hardening, if there are any surface bubbles break them with a pin. A heat gun is excellent for re-warming the surface. Even a lighter can be used to touch up or smooth the surface. Those who live in hot climates can let them sit in the sun.