Cleaning your sword after use or handling should be a priority, as if you do not then pitting, rusting and general steel degradation can occur making your sword cut less effectively or even become unsafe to use. There are many articles on how to clean and generally take care of your sword but I thought I'd do a more practical and hands on video on how its done.
This only covers the basics because thats all that is needed. I thought if I kept it short then you'd see the simplicity and find it easier to just get on and do it. It's like doing the dishes after eating.. apart from way cooler! Cleaning and re-oiling should be a staple thing that you do each and every time you cut or handle your blades. If you can't be bothered to clean it, don't touch it.
The materials used in this video are a Jay-cloth, Uchiko powder ball, Nuguigami cloth, Choji oil. These things can be picked up online with no problem at all and are relatively cheap.
Oops, I should of cleaned this sword last week and now it looks.. unhappy
If you've left your blade for a day or so without cleaning then shame on you. But on the off chance that you're human like the rest of us, you've probably done it too and you'll be glad to know the majority of surface stuff is easily fixed.
As always, this sort of maintenance shouldn't be done on expensive or historic swords.
There are also a couple of other things outside of actually resharpening/repolishing your blade that can be done to keep it healthy if you've forgotten to clean it straight away. Time to break out the Mothers Magnesium and Aluminium polish (or if you're in the UK and cant find any mothers mag, "peek" polish) is good for bringing a tired or slightly sad looking blade back to life.