There is no trick to assembling flat-pack furniture. There is only order, and the willingness to stop tightening things too early.
1. Count the parts first
Lay everything out and count against the parts list before you start. Every kit we ship has a spare of each screw, which means if you are one short, something else is wrong. Finding out at step nine is much worse than at step zero.
2. Leave every fixing loose until the frame is square
This is the single biggest difference between a unit that stands straight and one that leans. Cam locks and bolts should be finger-tight until the whole carcass is together, then tightened diagonally — top left, bottom right, and so on.
3. Build on a soft surface
A blanket or the flattened carton. Laminate and veneer scratch on concrete, and a scratched side panel is the one part you cannot hide.
4. Anchor it
Anything over 90 cm gets anchored to the wall. Not because the shelf is unstable, but because a child or a cat will eventually climb it. The strap is in the box; use it.
5. Two people for anything taller than you
Not for the weight — for the leverage. A 180 cm carcass is a lever, and one person holding it while reaching for a bolt is how units get dropped.