If using a thin plywood underlayment, screw down the underlayment with appropriate screws and check for any loose or creaky areas.
Fill any seams and nail heads with seam filler using a putty knife. Seams should be flat and smooth. Allow the filler to harden according to directions or 24 hours before installing the vinyl.
Clean away any dirt and debris from the surface with a vacuum.
Plan your layout. For large, open areas, draw a centerline down the room. Make a second perpendicular center line, to produce 4 quadrants. Lay out the tiles in rows just to double check you won’t have any awkward edges. Adjust line as needed.
Starting where the centerlines cross and moving in one direction to the edge, lay down enough of an area that you can do in less than 15 minutes. Use a V-notch trowel to spread the adhesive evenly.
Lay tiles or planks with tight fitting seams. Use a floor roller and a fair amount of pressure to completely flatten and bond the tile. Wait at least 24 hours or manufacturer’s instructions before walking on the surface. Reinstall baseboards as needed.