Human names are often extremley alien. Think of bushman names with click sound. Or think of French names and how unhappy your French teacher was with your desperate attempts at pronouncing them correctly.
It is not the strangeness and unpronouncability of a name that make it non-human. So there is no reason to attempt that. You are not writing for historcial accuracy. You are writing for your readers. A character name must make sense to your reader, within the frame of reference of your reader's mother tongue. This includes foreign languages the sounds of which your reader will be familiar with.
For example, for an English speaking reader, the frame of familiarity is English sounds, alienness is signified, to differing degrees, by Spanish, French, Irish, German, Scandinavian, Slavic sounds.
So if you want to invent a SciFi name for someone from the home culture of your protagonist, you use English sounds. Make up a non-existing word that adheres to the rules of the English language, and you got your name: Bilbo. Ged. Katniss. [Oops, didn't know "katniss" was the name of an existing plant. I thought that was made up.]
If you want to invent a SciFi name for someone from an alien world or race, use sounds from a language not native to but familiar to your readers: Elrond. Tehanu.
That way, the reader can read, pronounce and remember the names. They sound good. And they sound uncommon enough to be from the future or the otherworld.
Also, take note of the naming tradition of your genre. Fantasy names are very often Celtic or Norse, because the mythology that much of fantasy is based on is from those cultural contexts. SF names are often much more mundane, because they extrapolate current culture into the future.
You don't have to follow those conventions, but you should be aware of them and what it means if your elves have African sounding names, or your aliens sound somehow Asian.
Some authors on how they find character names:
These character names should be banned forever:
In "Dreams must explain themselves", Ursula K. LeGuin explains that she chooses character names whose sound is meaningful to her. I do the same. In the language that you are writing in, certain sounds will evoke certain characteristics, of people or things. This begins with the fact that male and female names are different and certain sounds, or sound combinations, are more prevalent (or popular) in male or female names. Other sounds sound hard or soft, bright or dark, elegant or quick, and so on. So what I do is define my character and his or her personality, and then get a large enough sample of possible names and select those whose look and sound fit my character best.
For my current SF novel I needed the name of the human female protagonist. I wanted the name to feel and look slightly exotic, but still familiar and not completele strang. It should be acceptable as a name today, maybe look like a future variant of a common name, sort of like Jula to Julia. So I downloaded the list of 40.000 names, deleted all the male and male/female names, and then scanned the file, deleting any names that I did not like.
This is faster than it may sound. I scroll the file and soon realize that I do not like the sound and look of names beginning with "V", or "Zh" or "J", so I can delete whole ranges of names. I don't like names ending in "drun" or "ise" (because they have a certain feel in my publication language), so I do a regex search with grep within TextWrangler to search-and-replace those names with nothing. I delete all names beginning with the same letters as other character names. After an hour of systematically deleting names with sounds or letters I find unpleasant or unfitting to my character description, I'm left with 173 names. I take another hour to look at each name, try to imagine my character with that name, and if it does not fit, I delete it. I'm left with 35 names that might fit. I google for images of persons of that name, and pick the name with the most pretty representatives. After half a day I have a name that feels perfect to me, if only because it is based on a selection process that leaves me satisfied.
I don't usually cast my characters (i.e. find images of real persons to represent them), because then I start writing the character to fit that person, but if I'm beginning to get confused during the name selection process, and all names start to feel equally fitting or wrong, I find an image that represents the most important characteristic of the character (e.g. the secret weakness or the final new identity) and open that image alongside my list. Then I match the names to that image. Later I delete that image and return to my own (and changing in the course of the plot) mental image of my character.
A powerful core sentence from the story outline (e.g. "She cut his heart out.") works fine as such an anchor also. I paste it into a separate file and have that open beside my list, so I always see. Then I compare the name with that sentence, sort of like a mathematical equation: does that name equal that sentence?
Lina ≠ "She cut his heart out."
Anu, Aive, ... = "She cut his heart out."
You can use anything that for you represents the core of your character: a piece of wood, a certain food, an activity or hobby, or a landscape, where she lives. Compare the look and sound of the name to this, and feel how it fits.
Depending on the type of story I want to tell, I use lists of names or lists of words (from different languages) to find my character names. I ususally don't make up new words, because I feel lost in the endless space of all possible letter combinations. But while I scan my lists, I might sometimes feel that a slight change to a word or a different representation of the same sounds will make the perfect name for me.
If my characters have first and last names, I always find the part of the name first that I will use for most of the novel. If the story is about a teenager and I and the other characters will refer to her by her first name, I find her first name first. If the story is about a politician and I and the other characters will refer to him by his last name, I will find the last name first. I'll then google for that name to see what first or last names it is often combined with, to get a feel for that. Often I just pick one of those names that come up, or make up something along those lines. I don't torture myself much over the part of the name that only rarely appears in my text.