Think preparedness. Think urgency.
I'm going to give you some ideas on how and when to clean your rifle when time may not be a luxury that you can afford. We will not be concerned with deep, detailed cleaning right now. We're more concerned about quick cleaning and how to best keep your weapon rust free and working for a very long time when you're basically doing it on the run. No matter how desperate things become, at some point, you will have to take just a couple minutes to clean and lube that weapon.
For the purposes of this tutorial, we are going to concentrate mostly on "field guns". The ones used primarily for self-defense, hunting and recreation. I am going to exclude precision, long-range rifles and also assume that you are using modern, domestic ammo. Although much of this advice will apply to handguns and shotguns as well, it applies primarily to rifles.
It has commonly been accepted since the dawn of time, or at least since guns were invented and started being used regularly, that you MUST clean your weapon each and every time you take it out and shoot it. Back in the day, in a time when black powder, cordite and corrosive primers were the norm, this was true. Those components were pretty quick to damage a barrel. Although many people still do clean after each trip the field or range, either out of habit or a sense of tradition, it is simply not necessary anymore. With modern smokeless powders and non-corrosive primers, you no longer have to fear the build-up and corrosion that the components of yesteryear created. With a very few exceptions, you can shoot your rifle quite a bit before you have to take the time to clean it. What's "quite a bit"? Well, lots of variables. To name a few; how smooth is your barrel? What kind of bullets and powder are you using? How clean was it when you started? How long is it going to sit before you use it again? The point is, you don't need to freak out or cancel any dinner dates because you forgot to clean your gun. There are some things that you should pay attention to though!
The first and most important thing is the outside of the gun. Surface rust can start to form literally in a matter of hours and will rapidly spread and ruin your finish if ignored. If your hands are sweaty or bloody or it is very humid, that process could speed up considerably. Generally, it is imperative that you do a quick wipe-down of the weapon before you put it away. A 20-30 second wipe-down with a soft cloth, slightly dampened with Breakfree, Militec or just about any kind of light oil will be fine, even motor oil. DO NOT USE WD-40! If the gun was dunked in mud or water or rained on, you should remove the stock and wipe down all exposed metal. Be careful not to get any oil on your scope lenses. It will attract dust terribly. If you do accidentally slop a little on a lense, use a very soft, lint free cloth with a little rubbing alcohol, a couple drops of gasoline or even hot water if you can't find anything else and get that oil off.
The least important thing about cleaning your gun is the action or internal workings of the gun. Unless it was really soaked in the mud, blood or beer, that can usually wait for quite a while. Maybe even a year or more, depending on what type of gun it is and under what kind of conditions it is usually used.
Now then, the barrel...
To stay in line with the premise of this article, I have one word for you... Boresnake, or something similar. Fast, easy and convenient, the Boresnake of the proper caliber is a complete, one-piece cleaning apparatus that will easily fit in your shirt pocket! Just put something like Hoppe's #9 on the brush of your "snake" and some more on the leading part of the rope, right where the transition between the lighter string and the heavier material is. Then put a few drops of light oil on the last few inches of the trailing end of the snake and you're ready to clean! Simply pull your Boresnake through the bore 2 or 3 times and you're all done! It's a good idea to keep a Boresnake in a heavy-duty Ziplock bag in your field gear or hunting vest as well, just in case you need to give your barrel a quick cleaning on the go. Of course, it will not replace a cleaning rod for knocking obstructions out of the bore. Probably the most compact rod for that purpose is the little 5-piece military steel cleaning rod.
Again, this is not to take the place of a good, deep cleaning but when you're in a hurry or have multiple guns to do or maybe even while you're in the field, this will do the trick and do it well!
Also there are lots and lots of excellent cleaning products out there that will do the job just as well. This is just how I do it.