Syntax [edit:] tip:
"try substituting tea or water for your morning coffee"
or
"try replacing your morning coffee with tea or water"
EDIT: For the downvoters: Fairly or unfairly, in the non-tech world people judge you by your choice and arrangement of words. (Compilers do much the same thing, of course.)
</pedantry>
Now, was the "correction" I just offered you effective and useful, or was it merely irrelevant, provincial, chauvinistic, uninvited, uninviting, and just plain rude?
(A note to downthread grammar trolls: I just used an Oxford comma, boldly, without apology. Have fun.)
That's a bit overstated. But mechanical_fish is right that that my own choice of words could have been more tactful. That's why I changed "Syntax correction" to "Syntax tip" in the GP.
Surely there are better targets for your editor's urges...
It's an issue of standard word meaning, not tech jargon. In the context of what 'muxxa appeared to be saying, his (or her?) use of substituting was exactly backwards.
What 'muxxa said was that caffeine seemed to exacerbate his RSI, and that substituting his morning coffee for tea or water helped. But the conventional use of the verb to substitute is to put or use in the place of another [1].
According to that conventional usage, therefore, 'muxxa was recommending putting his morning coffee in the place of tea or water. That seems to be exactly the opposite of what he was saying in the rest of the paragraph about the adverse effect of caffeine on his RSI.
Uninflected language is a pain. Ditransitive terms (substitute, comprise, etc.) are easily misunderstood at the best of times.