The alphabet shifting cipher, although useful for mixing up
the letters, has its own flaw. Frequency analysis. The use of finding common
letters forming a small word can easily destroy the point of a cipher. Finding
just a couple of letters, and matching them up will lead to the match up of the
other missing letters without the person ever having to work them out.
To make this method better would be using more fancy words
and synonyms of common words, to allude the cracker. Another would be to use a
completely different cipher with different symbols and keys.