Step 2: Add hardware
First strip out the existing interior of the suitcase, if you haven't already.
Because the case walls are quite thin (less than 1/4 inch) you might want to back all hardware with leather (see photo). Just cut a piece of leather to be slightly larger than the hardware to be attached. Glue the leather to the area you want to attach the hardware with some liquid nails. You also want to drill pilot holes before affixing screws as the wood used in these cases tends to be prone to splintering.
To reinforce my case I added two small hinges to the back and two draw latches to each side. Depending on the hardware on your case, you might want to add additional latches to the front, or replace the existing latches--leather backing can also be helpful for covering marks left by previous bits of hardware. If any screw tips penetrate into the inside, cover them with liquid nails before relining. You should be able to cover such blemishes during the re-lining process. Which luckily is the next step!