I write in several genres. Lately I've been thinking about naming my characters. When I write contemporary stories, creating the names of the characters is easy. We all know the names of people we know and ones we heard on TV and in the news. The one problem here with naming contemporary characters is having two characters with names that sound similar. This can confuse the reader and sometimes the writer. I try not to have two characters' names begin with the same letter. I also seldom use names like Spike or Belle. I do use these as nicknames for a character. Also things like Liz instead of Elizabeth. A writer also needs to know where the character lives or was born to find a name to match.
Historical novel names are different and call for research. I made a mistake in one historical novel by having the man named Drew, I should have used this as a nickname and named him Andrew. Also when writing historical novels and naming characters, there are names that aren't frequently used today, like Reginald. A perfectly good name in the Regency or other historical times. Some research is needed to find names that fit the period. Of course, many of the names we use today were common in historical times like George or Mary.
When it comes to fantasy or science fiction, I have a rule. The names must be readable. I remember reading science fiction many many years ago when the alien characters had names often many letters long that I never figured how to pronounce. I often skipped over those names. When writing fantasy, I look to make the names pronounceable and ones that might easily be read. I also try to give them names that almost sound like names we know. In one the character is Kylea. This was taking my granddaughter's name Kyla and changing it a bit. In my current book that's the fifth in the Moon rising series, here's some of the names - Ranal for a male and Amera for a female. Both are easily pronounced.
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So naming names of your characters can and should take time and thought.