It does look pretty bleak!
The easiest place to start is that patch of ground right up against the wall. Both walls. You could plant some shrubs
https://www.gardeningchannel.c... in there to brighten and soften the approach to the ? front door.
It looks like some kind of lilies around the foot of that tree; you could add a few (really, just a few; they'll multiply) bulbs in among them, as well as on the other side of the path. Plants that will grow taller and bloom at different times of year; say, daffodil, iris, allium and dahlia.
Then, maybe something hedgy - but less formal - along the edges of the property, to define your space. Maybe some forsythia, mock orange and pussy willow? If you're on a tight budget (like, who isn't?) you can start with just a few young shrubs, spaced fairly far apart - they'll fill in the gaps over time. Or raspberry canes... they don't look nice all year around, but they pay back.
If you're energetic, there is enough room, I think, for a flowerbed of perennials with maybe a birdbath or sundial in the center.
You don't give your location, so it's hard to recommend specific plants for your climate.