1. Top of the list of character names to avoid is weirdly spelt ones.
2. Tricky to pronounce ones comes next. I always struggle with Macon in The Accidental Tourist by Anne Tyler. Is it May-con or Mack-on? I was told authoritatively that Macon was an American city pronounced May-con, so it had to be that, but my American students struggle with it also. I realised after one class full of "Mack-on, I mean May-con"s we had finished the session by discussing 'him'.
3. At least Macon is short. Rumpelstiltskin is fine for a short fairy story, but imagine a whole novel featuring him. Worse, imagine typing out Rumpelstiltskin hundreds of times.
4. But sometimes a character needs a long name, in which case it's a good idea to abbreviate it. I once knew a woman called Anastasia Rodrigues. She called herself Birdie, which was charming. Rumpelstiltskin calling himself Rumpy would be less so.
5. Then there are silly names. I have met a child called Courtney Salmon, whose parents knew the pun and still went ahead with it, and there's always the boy called Sue but on the whole, silly names are to be avoided.
6. Inappropriate names. Names are often era specific and class related. There aren't many working class Ruperts, or upper class Chardonnays. My grandmother was called Maud, her sisters were Edith and Ethel, her brothers Harold and Claude, none of which are names you hear much now.
7. Which leads on to similar names. I'd advise against having Maud and Claude in the same piece of writing, and I speak as one who discovered the hard way that having characters called Jenny, George, John and Justine was a recipe for confusion.
8. For practical, writerly considerations I'd avoid names that don't pluralise easily - Tolkein ran into this problem with the party at the beginning of Lord of the Rings: when more than one member of the Proudfoot family were in the same room, did they become Proudfeet?
9. Then there are names ending with s - Davies, Thomas, Jones - unless you are very confident of your ability to use apostrophes and extra s's correctly.
Why does it matter? Because you want the reader to be absorbed into your fictional world. Anything that pulls them out of that world, even if it's only for a second or two as they ponder your punctuation, is to be avoided if you possibly can.
NEW!!! I've finally got round to organising some course dates....
How to WRITE a Novel: London 3rd May/Birmingham 7th May/
Oxford 8th May/Exeter 21st May/Bath 12th June
How to SELL a Novel: London 24th May/Exeter 4th June/
Bath 3rd July Details are on my website