[gr8fl4porsche]

As mentioned above, stand the sheets up - do not go through the trouble of installing horizontally.

Butt joints are very difficult for the novice taper. Standing sheets up gives you almost all factory beveled joints.

In commercial buildings drywall is typically installed vertically. In houses it is common to lay it down. Decisions are based on ceiling heights, wall lengths and wood studs vs metal studs.

In your case I would stand it up, assuming the studs are laid out properly. It is easier to add a stud here and there vs installing cut up sheets of drywall.

Also, I am a 5/8" guy. Heavier and a little more expensive but creates a stronger wall which may be nice in a tough environment like a garage.