My hiking boots are very important to me, having hiking boots in good condition means a lot when working as geophysical fieldworker, where I often have to walk up to 50 km. a day with heavy equipment with in all kinds of terrain.
In the perfect world I would every day when I return home from work clean my boots in water and every now and then give them a bit bigger haul over. I have gotten better at getting this done with time, but still I am not as good to my boots as I wish I was.
If it wasn't for the wear hiking boots get better the longer they are used, so good maintenance gives you good boots for a longer time.
I found this page which contains some nice advice on taking care of hiking boots, so far it's the best page I have found with advice for taking care of hiking boots but then again I am not an expert on this
I some time ago heard the advice of soaking a pair of new boots in water and keeping them on your feet all day for a long walk and then stuffing them with newspapers over the night, this should give a much better fit and save you from many hundred kilometers of walking in the boots.
I tried this back in August with a new pair of Lowa boots and it actually turned out to work much better than I had expected. Sure it still was a new pair of boots, but no blisters, and I had no problems with my feet during the months tough work that I was doing after this. I will follow this advice again next time I am to get a couple of Hiking boots.
Another thing that I have found is important is the sole, I have found investing in a quality sole like for example this one is well worth the money. After having replaced the not bad standard sole in my hiking boots with these soles I feel a lot less tired in legs and back after a tough day at work.