By trying each of the possible letters (excluding those you've already found) wherever the same cryptoletter is used, you can narrow down the possibilities.
Look for places which can take the fewest different letters.
Of course, some cryptograms might contain foreign words or names, so use caution.
Cryptograms in newspapers and magazines are usually based on a simple substitution cipher, often replacing each letter in the alphabet with a different one.
The letter A, for example, might be represented by the letter K, while the letter K is represented by the letter R.