Hello all ye merry tongue-makers!
I am guessing, from previous experience, that most of you have no idea what a phonetic system is, and yet you are positively sure that it is something confusing, complex, and not for you. But probably kinda cool, once you figure out what it is.
Well, not that you would believe me anyway, but, it isn't.

It is cool, but it isn't confusing or complex, and it is definitely just for you.
See, a phonetic system is what makes it so that you don't have to make a full language for your story, and still get all the benefits of one.
In fact, want me to tell you a secret?
I don't have any full languages. None. Zero. I have dozens of histories of languages (maybe hundreds), a couple dozen phonetic systems, a few structured languages, and no languages that are actually complete in any sense of the word. 
So obviously very few of us actually are able to make a full language. Most of us would, however, love to have some sort of language in our story. So how do we go about this?
We create an
illusion. * waves hands dramatically *
Some people call this a naming language, but I don't, because I call something else a naming language, and this is different. Haha. This is much simpler than even a naming language.
See, basically all we want to do is be able to randomly make words that
look like they belong to a language. What all is needed for that?
Consistency.
That's it! Honest! Of course, you can do more and make it cooler with extra stuff. Like you can make it into a full fledged art form and create essence maps to help you out and all that, which I do, but you don't have to. It isn't that hard, but it isn't necessary.
All you need to do is make these random words
recognizable as belonging to your particular language.
You can do that simply by setting up a simple set of rules about how you make your words in that language. You do it based off of what sounds go into the words and where.
For example. Let's say you have an elvish language.
And you list off all the sounds that are allowed in it. Start with the English sounds, and take some off and add some on (there are more, trust me, but you don't have to add more if you want). Fiddle with it until you have a list that has a nice feel to it that you like.
Then pick which sounds can start a word (or exclude some from starting a word). Do the same for ends of words.
And... you are done.

That really is all that is needed.
You can continue if you want, by deciding what syllable structures to use, for example.
Like, you can say your language only allows CV, CVC, and V syllables (C standing for consonant, and V standing for vowel). English allows: V, CV, CCV, CCCV, CCCVC, CCCVCC, CCCVCCC, CCVCCC, CVCCC, and more. It is very versatile. Some languages only allow CV. It is up to you. This right here is very simple to implement, and will make your 'language' a ton more believable and recognizable.
You can also make common sequences for specific kinds of words. Like you can make all city names end in 'ia' or all mountains start with 'kru.'
And on and on. You can have tons of fun with this, and never have to create a bit of grammar or vocabulary.