The best way to locate a suffix is to look for a word part that

Let's start from the beginning and try to under prefixes ans suffixes.

Some words (root words) can have words or parts of words added to the beginning or end that change their meaning.
If you add parts of words to the beginning of a word, it is called a prefix.
If you add parts of words to the beginning of a word, it is called a suffix.

This being said, the correct answer to your questions would be: 
The best way to locate a suffix is to look for a word part that is posible to remove. After removing the suffix, you will have the root word, which must be a word.

Hope this helps.