As suggested by the heading, this is going to be a teeny-tiny blog post – just a simple tip that will help you remember the difference between “discreet” and “discrete”.
discreet means careful, circumspect or unobtrusive, usually in relation to maintaining privacy (eg you must be discreet when working for high-profile clients)
discrete means separate and distinct (eg the two cities are run by discrete councils)
Here’s how I remember which is which: in the word “discrete”, the t is in between the e’s,* keeping them separate – which is, of course, the meaning of the word.
*Is that apostrophe in “e’s” making you cringe? Me too, but it is actually a legitimate usage, as we discussed in this post.