If you’re speaking to someone ESL, don’t do not even use contractions. They are perfectly valid but they are confusing to those new to the language. I also like to put all idioms in quotes when writing, as those are confusing in any new language. Misspellings are less of an issue than you might think because English spellings are dumb and arbitrary already.
When someone tells me “um, it is cacti, AKCTUALLY” I do not think concern for an ESL person listening in is the main motivation, though.