Well, probably the best advise is just to get interested in linguistics.
There are actually communities for people making conlangs (
constructed
languages), you can start there, people will most likely advise you what to do.
If you want some advise from me, well, it will all be about *how the language works* rather than *how it sounds* (because you'll always come across people telling you "this sounds like a mix of Hungarian and Japanese" or whatever). First of all: don't barrow any words from any languages known to you (neither from the ones you don't know xd), just make them. There is no chance words from a real language could appear in a fictional world, so there is no reason to doing so. You'll also have to think about it's grammar and that's probably the most important thing. I'll take my own conlang as an example.
Words in Padmaran aren't "working" like the English ones (or just the ones in European languages), they are derived from triple-consonant roots; all of the roots have their own meaning which *isn't* all that straight-forward, for example:
"
C-Ñ-R" means something like "eating/drinking" (Padmaran doesn't have a distinction between these two things), but a root isn't really a true existing entity, it needs some grammatical-morphological alternations to become a word; and that's the part when it gets interesting, because from one root you can make a lot of different words (I kind of borrowed this system from Arabic though):
"
Cañara" 'To eat/to drink';
"
Cañurna" 'To be hungry, to be thirsty';
"
Acñir" 'Food/drink';
"
Nucñir" 'A man who eats/drinks something';
"
Nucñira" 'A woman who eats/drinks something'.
And so on and so on.
One of the other things I came out with is that the nouns (which aren't different from adjectives in this language) have not only singular and plural forms, but also singulative, dual and nullar; what does that mean? I will give you some example:
Word "
Algê" means 'Elephant'. If you want to say that some elephant is big, you'd say:
"
Algê qaluran", you're simply using a singular number. Let's use plural:
"
Algêan qaluran", this would mean, that some particular elephants are big. Now the dual number:
"
Algêum qaluran", literally "Two elephants are big". Singulative number:
"
Algêar qaluran", which would either mean that there is some group of elephants which are big, or that the elephant is big as it is, because elephants are big. And now the nullar number:
"
Ilgêi qaluran", that would literally be "Zero elephants are big", which would simply mean, that there are no big elephants (which would be used in negations in the language, I won't really get into it).
Also some really interesting things like: word "
Naqeum", which means 'Mouth', is actually a dual number of "
Naqeai" 'Lip', just like word "
Aŝqeaizum" 'Scissors' is a dual form of "
Ŝaqqêiz" 'Blade'. Or even crazier things like: word for 'Horizon' is "
Alrinateum", which is basically construction of "
Alr" 'Ground', "
Natea" 'Sky' and dual number.
Also I have created a conscript for this language. I could go on with these.
What I wanted to show you is that the language get interesting when you start to talking about it's peculiarities.
