I'm not sure how much more intense 30-40 vs 20-30 will be... maybe it's not all that different in tensile strength. The main thing I recall is that the initial use of them seems so difficult and what you're really doing is developing a technique to get them on smoothly. Even now when I get a brand new pair, it's tricky getting them on. I bunch them up down to where the ankle is on the stocking, then pull outward a bit to try to stretch them and at the same time make that first move to slip them up over the heel. The trick is to not stop there completely or you're stuck with this vice grip stocking right at the ankle and it's hard to wangle it from there... so once you've got them over the heel... keep moving and wriggling enough to get up to the calf.
BTW, when I got my first Rx for a pair, I was measured at the pharmacy where I got them, so by what @blizzard2014 is saying and through my experience, maybe you need to consider getting measured and making sure you have the strength right. My first problem with swelling, my right foot swelled up so bad I had to buy a pair of boys runners size 12 or 14 I can't remember but none of my shoes fit at all. Now, I wear the stockings all day... just trying to get blood up to my lungs and head... Still, I'm dizzy as frack all the time like someone clobbered me.
Anyway, I hope you get some relief from them and get the right fit. Putting them on *does* get easier. :-)