I've said it before: that in my next life I am coming back as an international traveler. Among other things, it gives you a chance to be a practical linguist. There are people who pick up foreign languages easily. But you needn't be one of those to find the subject of language fascinating.
In a Walmart parking lot, of all places, I just finished talking to a French family who is traveling in the Southwest with their motorhome, imported from France. Eventually they will make their way to Argentina. I am proud to say that I did not start off the conversation with, "Soooo, whar ya frum? Do you gahs really eat frawgs?" I spoke with the father and his 10 year old son.
Speaking with someone who knows a little English is an intellectual challenge and pleasure. And it takes so much self-discipline! You must not grin at their mistakes, or be over-corrective. You must build their confidence.
Obviously you must speak slowly and repeat frequently, but it also helps to leave space between words, so that they hear words rather than just an uninterrupted stream of syllable gibberish.
If you are male, you must try even harder. We have ugly, low frequency voices that lack the clear enunciation of the female voice. (Recall your basic electrical engineering: higher frequencies mean wider bandwidth, hence more information. Women have broadband capabilities, one might say.)
In your own speech, you must continually reduce a complete sentence to a phrase of three or four words. You think that is easy?! This challenge is even tougher for someone who reads and writes a lot, because speaking is a lot different than writing. If you are so bumbling as to use parenthetical clauses with the foreigner, all is lost. Perhaps it helps to visualize English without commas.
Another mistake is using complicated verb tenses: "You could have gone there yesterday if it were not for the fact that it was Tuesday." This verbosity should be replaced with "not open Tuesday."
I see that I am falling into the famous pattern, epitomized by the classic quote from Horace, "Fleeing vice is the beginning of virtue." Reducing a negative has the same algebraic effect as increasing a positive. But in a new endeavor, reducing a negative is the fastest way to make progress at the beginning.
But you can only go so far with that approach. Then you must move into expanding the positive, where your approach becomes somewhat vague, open-ended, and slower. And yet wonderful.