Purchase the largest size of panels available. Most ceiling panels come in a few standard sizes. This will help you to avoid having a lot of seams in the installed paneling.
Install the ceiling panels as tightly as possible. This will minimize the visual effect of the seams in the ceiling that are caused by expansion and contraction.
Install the ceiling panels per manufacturer directions. Although manufacturers recognize that there will still be seams in the ceiling panels, the instructions they give will help you to minimize the appearance of the ceiling panel seams.
Finish seams between ceiling panels with colored caulk. Match the color of the caulk to the color of the ceiling panels. Load the caulk into a caulk gun. Cut the end of the caulk tube with a utility knife. Apply a bead of the colored caulk to the seams in the ceiling paneling. Smooth the caulk with your finger. Carry a damp cloth with you to wipe off excess caulk from the ceiling.