How to write in English for international readers? [closed]

How to write in English for international readers?

I'm not a native English speaker but I've been learning the language for many years in many fields (Mathematics, Physics, Mechanical Engineering and Programming to name some). Every now and then I find something explained in 'basic' English that I just cannot figure out without some search. Along the way I learned some small tricks for writing English for foreigners.

Assume that the reader has an intermediate-high English level to answer this. The reading fluency is the main concern in this question, not the learning of the reader. I also wanted to give my 2 cents in this so I'll answer my own question in community wiki format, so please add your advice there.

This question came up to me after reading the word 'Jeopardy!' in this stack overflow blog post.

EDIT: I read this afterwards (which seems pretty mistaken):

John Saunders: I wonder what proportion of StackExchange users don’t know what “Jeopardy” is?

Jeff Atwood (author): @john I suppose the same proportion that don’t know what “Wikipedia” and “Clicking a Link” is.

Make your English readable internationally.

After some investigation myself, I found this and this great articles, which I'll use to complete what I already learned. Note that, since this is for intermediate-high level foreign speakers, I omit some of the advise in these articles (they understand perfectly 'It is...').

Use short sentences.

Relatively short sentences are easier to digest and understand. Furthermore, they are also easier to translate by automated translators. A 5 lines sentence is difficult to read even for most native speakers.

Don't use anything that is on the TV

This includes mainly TV programs (as Jeopardy!), celebrities and jokes. How would a Spanish reader know what is the meaning of "Legen...Wait For It...Dary" when they have it translated and it's not even so popular there. Although if you must talk about them...

Include visual content!

Many TV programs have similar ones in every country (for Jeopardy, Saber y Ganar in Spain), so they might recognize easily what you're talking about if you include a picture. For celebrities, they might have seen the celebrity before somewhere in a movie, show or online, so a photo will help greatly. Anyhow, pictures and visual content is widely advised for writing online.

Write in the same way 30-50 years old people do.

The average age of teachers is that one. Foreigners are taught normally by teachers. So the English they're being taught is the one that 30-50 years old people speak. Furthermore, these teachers learned English when they were younger from other 30-50 yo teachers (only reinforcing my point).

Urban Dictionary is evil

If its meaning is only in Urban Dictionary, you better don't use it. If you must use it, include some link to the meaning or a small quote of it. Foreign students normally speak in their language, so no new jokes are learned about the English language.

Please, consider adding more or improving the ones added.