What do you want to use your yard for? Gardening? Badminton? That makes a big difference. I note your path to the water is skimpy.

It would basically be an area to sit and enjoy the lake with adirondacks and possibly a dining area. Above all, we want to beautify with landscaping. The path you see leads to more significant stone stairs going down to the dock.

I suggest emphasizing the walk down to the water. Keep new landscaping low. Select a few trees to remove to improve the view, A flower bulb garden or wide (like 5 feet) native blooming perennial border would be lovely. Good photos here: https://www.houzz.com/magazine/10-beautiful-ways-to-landscape-with-bulbs-stsetivw-vs~3880424

Spring Flowering Bulbs in Shrub Border · More Info

To me there is a perfrct spot down by yhe lake for a firepit on that concrete and maybe just huge pots filled with seasonal plants and the flagstone topping is all you need .