There are several approaches that can aid in developing your palate.
The preferred method of tasting coffee. This requires only a cupping bowl and spoon. Dose out coffee, pour in the hot water evenly, and at 4 minutes skim off the top to remove the crust while carefully not disturbing what has settled at the bottom. Wait about 12-14 minutes for the coffee to cool to a desirable drinking temperature, and slurp the coffee with the spoon.
Types of flavors
There's a variety of descriptions you can use to describe the coffee. Try describe everything. The mouth feel: is it full bodied or light? The acidity: Is it citric or stone fruit? The Smell: What are the aromatics?
Every time you taste coffee, keep notes of what flavors you taste. Basic notes of chocolate or smoke are fine, more nuanced flavors like cherry or plum may come out. Don't be afraid to write exactly what comes to mind. If the coffee tastes like captain crunch then write it!
Don't just taste your coffee by itself. Compare it to other roasts you've done. Compare it to coffees from other cafes as well. Note the differences.