Make sure the name is something easily pronounceable. Add some dialogue to the story to explain the pronunciation if the pronunciation is not obvious. Use unusual alternate spellings of names only if it says something about the character or the story itself. Using "Tiphanee" instead of Tiffany is likely not the ideal name for a lawyer in a serious crime drama, though it might be more appropriate in a comedy or a novel driven by character.
Use culturally appropriate names to make the story realistic. Use a traditional Arabic name, such as Ammar, in a story about 15th century Persia, where you would be hard pressed to find a Kevin.
Keep the size of the first and last name varied instead of making them the same length with the same amount of syllables. Vary this length to keep the sound pleasant and easy to say and to remember.
Vary the sounds and sound groups in the name instead of introducing rhymes or other cutesy elements into a name. Use a cutesy name if it's appropriate to the story, but keep in mind that the joke can easily get stale quickly in the reader's mind.
Give all of the characters names that work well together. Let all of the names work together to add to the tone of the story instead of giving one character a name that stands out too much to be plausible.