Remove door sills, and kick panels. Clean and paint floor as needed.
Relax carpet by placing it in sun light to lessen wrinkles, and allow it to lie into floor contours.
Have a utility knife with several new replacement blades available. Don’t use dull blades change as needed.
Work from center lines marked on carpet and floor. If two section carpet, install rear section first.
Once carpet is centered and any shifter cut-outs made, flop one side of carpet over along center line apply spray contact cement on half of transmission hump, slanting floor of foot well at fire wall and back of carpet, and flop back into position. You will have to work it a little bit to work out most of the wrinkles, and get it centered. Repeat process on other side of car. Spray contact cement will allow easy readjustment of carpet if needed, so take your time and mind your centerline marks, and keep carpet snug to hump, and fire wall.
Fit carpet to door openings, allow it to ride up over door sill enough to be held in place by sill moldings. You may need to spray some contact cement to slanted portion of floor along door openings to get carpet to lay in. Do not use glue on flat sections of floor so any wrinkles can relax out over time in the area.
Seat bolt holes can be located by inserting an awl or ice pick up from under floor through carpet. Cut a small “X” about ½ inch over bolt hole with a utility knife sporting a new sharp blade, and mark each seat hole with chalk to make installing seats easer.
Use awl to locate existing screw holes along door sills, and kick panels to make life easier…
Work slowly, mark all cuts first, cut less then make a trial fit, cut some more if needed.