This is an area I have been fanatical about,since buying my Avalon Ascents some years ago.They have a gorgeous olivewood finish that cannot be had,due to deforestation .I used to collect Martin guitars,and even with their stunning gloss finishes Martin had no problem with polish,so long as it was their polish in use.
What I have done(I did have a bit of woodworking experience,years ago)was to find the finest furniture polish available.I was very careful about the ingredients.It seems that natural oils is a GOOd thing,in that it will not penetrate a good finish.It will help protect against what is called "finish checking".Even if some were to meander into some grain,it most likely would moisten,slightly,and help keep it from aging.Just wipe thoroughly(leave no residue).We have all seen this.Just look at the grain pattern on an old piece of furniture.If it's a long grain hardwood,you will most likely see a slight seperation(actually a splitting)at many of the grains.This is normal,yet can be GREATLY reduced by the regular use of one of the better products.I use Weimans furniture cream.Damn expensive,and available commercially.Truthfully,my speakers really Do look exactly as they did after unpacking.Knock on wood.I told you I was a fanatic!Sorry!I buff,with this before every seasonal change.
Also make sure you have a good humidity level in the room.You can always get a digital humidifier to run,if you don't have one in your main heating system.This is important.
Also,a soft flannel cloth is actually better than a cotton shirt.Cotton is more abrasive than flannel.Cut up some old P.J.s!!Heh,heh!!
Best!