How can you safely clean a vintage suitcase / trunk / chest?
The first step is to ascertain what the piece is made from. Leather will need careful cleaning with a leather cream or wax and a soft cloth. Soapy water and a sponge will clean a vinyl suitcase.
A vintage trunk and chest made from compressed fibre or wood can be lightly rubbed with a good quality natural wax and fine wire wool (000 grade), the wool will remove the dirt and grime, finishing with a soft cloth to bring back the original colour and a polished finish. Wooden chests with many years of using and deterioration will need a coarser wire wool such as grade 0 or 1, to start, followed by a fine grade.
What steps can be taken to ensure it stays in good condition?
Avoid placing suitcases / trunk / chests in direct sunlight or next to a heat source such as fireplaces or radiators as they tend to dry the leather or wood which could result in cracking or splitting. A good quality natural wax or leather cream applied several times a year will keep your suitcase or chest looking good. Oil hinges and locks occasionally with WD 40 or similar.