I do get some water in during heavy rains in two areas that are low that I know I want to build up. Also, in these two areas, the gutters dump right at the foundation, so I not only want to built it up, but exit them away from the foundation.
If you can swing the $$ I'd start by re-doing the curtain drains to end the water issue. Looks like you could do it yourelf with what looks like a tractor. TO me that is most important. Then I would lay out a rough sketch and tackle one zone at a time. One thing I would consider is hardscape for the cement stair area. I'm a fan of Pennslyvania Blue Stone. Weeds were mentioned but if you do it correctly they are rare. Stone on top of cement gives no weeds UNLESS you have a compromised area like a cement joint where a spore takes hold. Pretty easy to deal with.
I'd look to start with stairs and rip out all the existing plantings. Digging all the roots out. And I'd get that large stump drilled and some commercial product in the holes to kill it quicker. I went with a rental grinder and it was ok but work and not a perfect solution.
Consider wind direction(s) and sun exposure. Nice to have a deciduous tree/shrub of size and height to help block windows that get sun in summer but allow sun in during colder months. I'm not a planting guy so I lean shrubs and dwarf trees. Many magnolias can be found to be 8ftx8ft (love mine) and hearty in my zone of NY. I've had 14 dear daily for years in the back and they never ate the Magnolia. Always remember spacing is critical!! When figuring out what to plant try and think of tall and thinner shrubs (I like evergreen for this) help to break up and sharp corners or areas of transition your home might have.
I used a mix of burning bushes, different hollies, walking stick, magnolia, dwarf Alberta, weeping evergreens do well at corners. Lots to think about. Lay it out on paper and take your time.