If you want to get by and have a better chance of being understood, you have to speak to people in a different way than you would to another fluent English speaker. Here are some tips for speaking to English beginners. Of course you'll adjust things as needed for people with a better handle on the language.
If you haven't spoken to someone who speaks fluent English for a while, it's such a shock once you finally do! It's so easy and you can say so many words and speak quickly!
Speak Slowly and DeliberatelyYou should not only speak slowly, you should speak ridiculously slow. If you have ever learned another language, you know that it takes time to process each word in order to understand what someone is saying.
Speak clearly. Enunciate each word so that the person you're talking to has a chance at recognizing the words you're saying.
Most non-native English speakers tend to learn English with an American accent so those of you with, say an Irish accent or Indian or any other heavy accent, need to be even more deliberate with your enunciation. After you've been in a country for a little while, you'll start to recognize how they pronounce certain English words. I find myself tending to use their accent so I'm better understood.
Limit Your VocabularyUsing simple words is a biggie since non-native speakers will have a limited vocabulary. Think of words a child first learns. Like you should use the word "sad" instead of "unhappy" or "happy" instead of of "thrilled".
This might not be the most polite way to put it, but dumb it down. I speak some Spanish and I'm always so grateful when someone speaks to me slowly using simple words that I'm actually likely to know! I will even ask people sometimes to speak to me like I'm a 3 year old.
Don't use contractions. Say "do not" instead of "don't". For those with even more limited vocabulary, instead of "do not" "cannot" "is not" etc., just use the word "no". "I no want coffee" or "I no go today" or "he no have money".
Use the word "more" for comparative and superlative adjectives. Instead of using the word "better", say "more good"; "more bad" instead of "worse". They might know the word "good", but might not now "better" or "best". It might not always be proper English, but you are not giving English lessons; you are trying to be understood.
Only Use Necessary WordsLeave out words that aren't imperative to making your point. Rather than saying "Do you think it will rain today?" (all rather easy words) say "Rain today?" or instead of "What time will the bus leave?" say "What time bus go?" (pointing at the invisible watch on your wrist).
"I don't really care for eggs." = "I no like egg."
"I would like to go to the beach today." = "I want go beach."
"May I take your photo?" = "Photo okay?"
Try Different WordsIf someone doesn't understand you, first repeat what you said in case it just didn't sink in. If that doesn't work, try different words. You might not have hit upon the particular word they learned for what you're trying to express.
Like if the word "fear" doesn't work, try "afraid" or "scared". We asked our guide in Komodo "What do you fear the most?" Nope, he didn't understand. But when I said "Scared snake? Dragon?" he totally understood. My friend asked some Russian guys "Did you get a chance to clean up?" and they didn't understand. But when I scrubbed my arm and said "Bath?" they understood. And yes, they had indeed bathed. ;)
Ubiquitous WordsSome words will work almost anywhere, removing some of the guess work. See Ubiquitous Things - Phrases, Food, and More for more details.
The words "okay" and "no problem" are understood worldwide. "Finished" is an important one, "take-away", "photo", "selfie", the international charades motion of signing your name in the air, and pointing to the invisible watch on your wrist are all super useful!