Some people bring props to the gaming table; carefully drawn and aged maps, coins, letters, beautifully painted miniatures, and what have you. I bring languages.
I dabble in learning languages, and can speak a few phrases in half a dozen besides English, all though I’m by no means fluent in any of them. So, when my players encounter NPCs or monsters from another culture, and none of the PCs speak their language, I use another one. (If one of the PCs can speak the relevant language, well and good; play continues in English and that PC is assumed to be translating.)
In Irongrave, for example, the Common Tongue is represented by English, the Noble Tongue by French, Urosman by Italian, and Orcish by Russian. Those were selected partly because I can say appropriate things in them, but also partly because of what the likely players speak – in the UK, everyone has to learn some French at school, so like their PCs, the players have some idea what is being said in Neustrian even if they don’t speak it. The players most likely to play scholars know a little Italian or Latin. Nobody except me speaks any Russian, so I picked that for Orcish.
When last running Traveller for a face-to-face group, I used English for Solomani and Vilani, Russian for Zhodani, and Japanese for Aslan. Although I’m learning Turkish now, so if I ever run a game with Aslan in it again, they’ll speak Turkish.
In 2300AD, our campaign was in the French Arm, so English, German and French came into play. The kafers spoke German, because in-game that was the first human language they learned, and the pentapods spoke English with fractured grammar, heavily interspersed with random quotes from old adverts and famous films – “From far away have we come to see Famous the Bill, good to the last drop, Pilgrim.” During the course of the campaign, the players eventually figured out that an unscrupulous trader had sold them a box full of old DVDs, claiming they were language tapes.
Try it. It’s different, it’s very portable, and it links particular cultures or races to stereotypes without the players even realising it.
Haven’t studied any languages? You still know some Spanish (from watching Western movies) and German (from watching war films). Or you can use dialects and accents; see how many different types of English you can spot in Star Wars.