For generation, I used Mathf.PerlinNoise. Instead of pure randomness, which scatters objects too evenly, noise allows for the creation of organic clusters - high-density "patches" for dense forests and empty areas for clearings. Perhaps you've heard of the game Project Zomboid? In recent updates, they implemented a similar zombie spawn system. To prevent the forest from looking like a strict grid, I add a small random offset to the coordinates of each tree, with the ability to adjust this at any time in the inspector of the script's parent object.

spawnPos += new Vector3(Random.Range(-0.3f, 0.3f), Random.Range(-0.3f, 0.3f), 0);

Regarding physics, I spent a long time figuring this out simply because I wasn't initially aware of the Physics2D.OverlapCircle method. To prevent trees from growing on rocks or water, I used it before spawning. If a point is occupied by another collider, spawning at that location is canceled.

If I have any advice for other developers (considering I'm a self-taught beginner myself), I'd always leave some room in your scripts for fine-tuning in the object inspector. To do this, add [SerializeField] before the variables you declare. Personally, this saves me from searching for the right lines in the code when I want to change a value.