I did my 90 740 Wagon, and It was the first headliner I have ever tackled. It cam out near perfect, and that included re-doing the sunroof. Here's what I did. Go to the ipd site and download the instuctions. Go to a local auto upholstery shop and buy your 1/8 inch foam backed headliner material. Enough for my wagon cost me $60. Buy the best quality spray adhesive for headliners that you can find. I got mine at the same shop that I got the headliner material, can't remember the brand, but I do remember it was marked "hi-temp" since I live in the South where car temps can get pretty high. Guy at the shop said some brands will eventually fail in the summer heat and start to sag. Anyway, it was about $15 a can. NOw that you've got all your stuff, read the ipd instructions and read the 700 FAQ posts about doing the sunroof. Priceless advice in there!! The only thing that isn't perfect on mine is that I didn't clean out the inside of the sunroof mechanism before sliding my newly covered panel back in there, and some of the broken-down glue from the old headliner stained my new panel. Minor, don't notice it unless I look for it.

Don't be scared, just be patient and save yourself $100s of dollars.