How to treat a wood door to make it look good for a long time?

Question

How to treat a wood door to make it look good for a long time?

Answer 1

I must assume you refer to an exterior door, and you wish the wood characteristics to remain visible?   I'd suggest using outdoor polyurethane on it.  You can get high gloss (though it tends to highlight any defects in the wood grain or seams), semi-gloss (a good all-around choice) or satin (outstanding at hiding defects).  

Another choice, though not as durable & requiring re-coats every few years, would be exterior wood stains that can provide color yet retain the beauty of the wood grains.  This is a good choice for those that prefer to continue a color scheme to the entryway.  

You can always go to a local hardware or home improvement store and browse their selections to get a better idea of what you would like.

Answer 2

Don't slam it too much, don't bump into it or scrape it with hard objects, or othewise abuse it.