1.Make your sidewalks & paths curving instead of straight, wider than normal, and out of something other than cement - pavers, mulch, pea gravel, stepping stones . . .
1a. Sculpt your ground, so that it's not dead flat.
1b. Make 'berms' and plantings such that not everything is revealed all at once.
1c. Choose a color scheme in your plantings that appears cohesive and try for color in every season.
2. Plant thickly in layers and groups. That is - a groundlevel layer like ground cover or lawn, a taller layer like small shrubs, ornamental grasses or perenniels, a still taller layer of 'short trees' like dogwoods, crab apples, etc. and keep them pruned. Your upper story is your existing trees. It make take a few years before the look matures sufficiently to satisfy you.
3.Acquire (or make) quirky lawn ornaments and tuck them in unexpected places. I have a (now faded) red alligator cast in a mold from resin and tiny sand sized pebbles, a "mosquito" made from a shovel head, rake, rebar, a saw blade, etc, a set of Alice in Wonderland resin figures (except for the mad hatter, who lost his head), and an old mill made of wood, until it disintegrated after a tree fell on it. One of my paths is "foot shaped" stepping stones about 18 inches long, set in a mulch base.
Hope this helps get you started. I've been working on mine for 20 years.