It pays to approach every chisel task knowing the most-appropriate method before you put steel to wood. These techniques will get you through virtually every job involving a chisel.
This skill entails removing a lot of waste quickly, such as when cutting mortises or dovetails. It requires the considerable force of striking the end of the chisel's handle with a mallet. Though many fancy wood mallets exist, I prefer a plastic dead-blow mallet for chopping—it won't mar the chisel handle and can deliver plenty of force.
For a good chopping grip, wrap all your fingers around the handle. Always chop with the workpiece clamped to a rock-solid surface. Hold the work stationary between bench dogs, secure it with a holdfast, or clamp it to a board held in a vise. Don't try to hold the workpiece between vise jaws—it will move with each mallet strike.
For refined work, such as cleaning up mortise side walls, tenon shoulders, dovetails, or even small miters, use hand force only to drive the chisel forward, removing no more than 1⁄32" at a time. Again, always clamp the workpiece; never hand-hold it.
For best results, use a classic paring grip. When paring tasks call for extra downward pressure, such as cleaning up tenon shoulders, try a modified chopping grip, with your thumb over the end of the chisel handle, using your other hand to guide the blade.
Use this method to cut pegs, dowels, and other projections flush with surrounding wood. Hold the chisel in a paring grip and use the other hand to hold down and pivot the chisel. Again, don't try to remove too much at one time.
A sharp chisel works great for cleaning up glue or evening up surfaces in tight areas. Hold the chisel handle with a modified chopping grip and use your other hand to pull the chisel blade toward you—hold the blade low to prevent chatter.