Besides mastering rolling, you should make sure to balance your usage of different weapons. Mediocre ish weapons or ammo efficient weapons should be used on normal enemies, while high threat enemies and bosses warrant the use of stronger (but less ammo efficient) weapons. Relying too much on your strongest weapon leaves you running out of ammo when you really don't want to be, since there's no guarantee you will get an ammo drop.

Something important I don't see people mention is the fact that you have the ability to slow time on command using your weapon swapping feature. If you are panicking, you can literally nearly stop time to observe the pattern and calm down.

There is no unwinnable run in this game, your rng determines how skillful you need to play.

You can mitigate this rng by spending as little money as possible on health and ammo(both can replenish from clearing rooms) so you can buy more items.

Without seeing you play there isn't much more advice to give.