Two jobs shape these days, keeping swelling down and keeping the dressing safe, and everything below serves one or the other.
Sleep is what most people forget. The hand should stay up all night, and a pillow beside you beats your chest, which you will roll off in your sleep. A sling is a daytime thing and usually comes off in bed, but your discharge instructions outrank that rule: if they say keep it on at night, keep it on.
You will be using your other hand, so keep everything on the good side of the bed, and set out shirts you can pull on without touching the dressing. Take off rings and any jewelry that might catch on the hand or arm, before swelling makes them hard to remove.
If the splint or cast feels too tight as the swelling rises, do not cut or loosen it yourself; that is a phone call, not a pair of scissors. And keep the dressing dry.
Take your medication as prescribed rather than waiting for pain to climb, and expect the hand to throb whenever it hangs down.