If you are writing a comic or satirical novel, then the names you choose don't have to sound that realistic, but one golden role for these styles of books is ... be careful that that a real-life person you might be satirizing cannot identify themselves, as this can lead to legal ramifications. I have had several clients who wrote about real people in a less than disguised way, and I steered them all clear of this course of action. Even though a book might seem funnier if their names are left as is, it is never worth going to court over.
Tip One. If you are writing a work of historical fiction, always check that the names you have invented were not actually real people - this could always confuse the reader, if they are very well-versed on the subject or period in history that you are writing about.
Tip Two. Write down all of the leading and supporting characters of your work and change the names of any that sound too similar. This might seem like common sense, but many writers come to me for help with their work dotted with people's names that are so confusing. You see, it is one thing inventing a name, writing it down and thinking that it looks different to another - but how does it sound when spoken:
i.e. Mrs Brun and Mr Brown,
Miss Fortesque and Mr Askew,
Master Plewitt and Miss Drewit
It is well worth the time of any writer to read each character name out loud after inventing it - if it's hard to say, then do forget about it and re-name the character. You will need to think further down the line about possible audio books, stage plays or even feature films - and you don't want your readers/audience to be confused.
Tip Three. Shakespeare was a master of writing names that described people perfectly - so much so that you did not even need to see the actor playing them to realise what the following characters looked like:
Sir Andrew Aguecheek, Puck, Caliban and Tom Snout are just some examples.
Think of how you can make your characters come alive with the names that you give them.
Tip Four. When you have your list of around seven main characters, then write a back-story for each of them.
Do some people have a name that has come down the family line with an unusual spelling?
Do some people have initials rather than one or two first names? Is that because they are trying to hide something about their past?
Finally, think of androgynous names such as: Andi, Blair, Jodi, Charlie or Dale - there are many more than these examples too.
Why would your character be named this way?
Have they changed the spelling of their name at all? Why would they do that?
Also, are they ashamed of the real name they were given at birth.
You'll find that playing around with names and back stories will get your project off to a flying start. Good luck.