Generally, if you're having difficulty, aim for corners or edges, those are the main snapping points. It's a bit sensitive and may take some finer aiming with some pieces and angles, but you'll likely get the hang of it after a bit. Also consider the angle you're building from; it's easier to extend things downwards from below, easier to build up from above, etc.

Honestly I consider the building in Valheim better than that in other games because there are few restrictions when it comes to overlapping pieces or overlapping with the terrain. In games like Rust and Ark, you need to build in a flat area, work carefully around terrain, and avoid overlapping pieces. Because of this those games have only a handful of particularly viable building spots and even less variation in building styles. In Valheim, some pieces might be more tricky to place correctly, but you have total control over both the building and the terrain itself.