Once you have medical clearance and guidelines understood, one of the main things is to make sure they are avoiding the valsalva maneuver/holding breath.
Here is an article I found. I didn’t read it all, I just glanced at it a bit, but it seems to include the basics.
ALSO, in case you do not know, some medications give false readings /measurements of exertion. Someone’s pulse and/or bp can read lower than their actual efforts due to medications.
ACSM has info on this and I figure IDEA might too.
Just have fun and be safe, that helps a lot too!