What is in a name? In real life, not all that much to be honest. Out in the real world we get to see how people look, we get to form an opinion on how they behave. The way we view others are based on actual experience. Not so when it comes to fiction. No matter how detailed a description may be, it will never be as chock-full of information as reality. The amount of data we acquire just by looking at a face for a few seconds would be enough to fill a whole novel. So in the fictional world, a name can be an enhancer, it can add flavour to a character.
If you imagine a man named Jack and a man named Jake, the mental images will undoubtedly differ. A woman named Helen and a woman named Helena will conjure up two distinct faces. The differences may be huge or they may be tiny, but there are always differences, no matter how minute. This is of course due to our brain’s ability to remember specific traits in people, sometimes subconsciously, and to relate them to different names. If you meet enough people named John who are tall, you will imagine a tall man the next time you hear the name John. In short, brains are awesome at putting pictures to words. It is sort of a short-hand for the brain, where information is more quickly retrieved by using shortcuts. And that is something that can be used when naming your fictional character.
The problem there is that not everybody has the same mental images. For example, I see Jack as a burlier, gruffer person than Jake. Helen to me would be fairer, while Helena would be darker. No doubt these names generate different variations in the minds of others. But there are names that are generally similar in what image they produce. Jedidiah. I doubt anyone thought of a Seattle hipster when they heard that name. Arnold. No one imagined a scrawny little kid upon hearing that. Things like that can be useful when choosing names. Arthur or Oscar would be a more suitable name for an old country doctor than Ajax or Orion. Unless of course the discrepancy between the character and the image their name conjures up is what you are after. Bob wouldn’t normally be the most suitable name for an old wizened wizard, but it could be just the right fit for your story. Names sure are a tricky business.
Another thing that is important is to keep an internal logic in your story. If you write a story about viking-like characters all named Thorvald, Harald, and Grim, it is going to look really weird when a Jim suddenly pops up. Nothing wrong with Jim of course, but without a solid explanation for such an out-of-character name, much of the immersion will be shattered. We don’t all have to study linguistics like Tolkien to keep the names sounding real in the confines of the story, but some level of consistency is absolutely vital. Names that sound to come from wholly different cultures, or even times, are always an immersion breaker. And this applies not only to made up names in fantasy and science fiction, but also to contemporary stories. If you pick nothing but names from some list of obscure given names, that will also break the illusion. Not everyone can be named Blaze or Electra. Throw in a good old Dave or Lisa for good measure. More common names are nothing to be shunned.
Anyways, I think I have confused you, and myself, quite enough for one day. Now I am off to figure out what to do with Bob the Wizard, because that actually sounded like a pretty fun idea.