My novels contain several fictional races, but I have been trying to decide how to name them. Therefore, I must ask: is it more common for science fiction/fantasy writers to completely make up the names of races or to use words from other languages? I have seen examples of both (for instance Darth Vader means dark father). I wish to use the less common method, whichever it may be.
In general, it can be both. Authors will often take a foreign language and edit it into a new language. For example, Tolkien's elf language was based off Finnish, and in fact, he was linguist. A reason why he made lord of the rings was to have somewhere to use his made up languages.
Because of the sheer difficulty of simply creating a name off the top of your head, I would have to say that copying another word and editing it is the more popular method.
On a side note, I should probably point out the amount of endings that are cliche in fantasy. They include: -dell (surrendell), -far (fellenfar), -fell (evenfell). Those make it so easy to make new words, that I literally thought of those examples off the top of my head.
A tactic I personally find helpful, is to say your idea's out loud, and see if they actually sound good in a sentence. Like, "The Urterall armies are going to attack.". I should actually point out how 'urgal' from 'The Inheritance Cycle' inspired me to think of that just now. I took the -ur sound at the start of the word, and took it from there.
I hope this helped with naming your races!
If you are looking for the less common way, the most prominent way is to use combinations of foreign languages and meld them into a unique one. This is often great for an English audience that is not fluent in other languages, but if you are planning on selling your novels internationally, it might shatter the suspension of disbelief if a reader sees a word that they know. Overall, I believe that maybe taking some words from different languages and changing them slightly might work, as it is easier to write, but it might be more interesting to make a whole new language and really catch your readers off guard. I hope that helps at all.
You could use letter substitution ciphers or anagrams to make different versions of short English words with basic meanings. Then modify some of them to sound better. If you do this with a few hundred basic English words you will have a few hundred basic words in an imaginary language.
Then you can assemble them into words and names each consisting of 2 to 4 of the short basic words. And modify some of them to sound better, assuming that the speakers of the language have done the same over the centuries. Your readers will thank you for that.
And you can do the same for several languages in your story if it is a science fiction or fantasy novel with lots of characters from different societies and cultures.
Some of your characters might sometimes react to the liternal meaning of some of the names, especially if they think they are not very appropiate for those ho have them.
And other characters might sometimes react to the associations of a name:
"Your parents named you after Bloktar the Terrible?"
"No, they named me after my great grandfather, Bloktar the Humiliated. They hoped I might bear up to that accursed name as well as my great grandfather did." "Did you kill your parents?" "No, but I'm still considering it."