It's really easy to run further. Take another step.
There's many things that I could say: Eat lots of food, drink water, stretch well, rest well... but the most important thing about learning to run further is to take that extra few steps and go further. If your limit is one mile, the next day, run to that half mile point and run a little further, to the next mailbox, tree... something, and run back. If each day you go just a little bit further, eventually, you'll be able to run a lot longer than you have ever thought of doing. You might make a day once a week where you go off and run your longest and slowest runs, going further than you have ever gone, even if it is a little slower.
Having that one day a week where you run longer than the other days will help push your body to increase its stamina. Just once a week is enough to raise an individual's ability to run further. Eventually, because of that certain day, you can start running slightly further in your normal days, and keep running further on that one day. One day can make a difference, because it allows you to test your limits, pushing your potential, and little by little it will overflow into your average day (should that be your goal). The stamina increase of one day will easily affect you in a positive manner.
Honestly, if you run every day, you are already giving your body a workout and increasing its stamina and perseverance. Long and easy is the way to go if you want one day a week to increase your stamina, and depending on what your goals are, you could even do 3 days a week of long and easy running. If you want to build your speed, and little by little increase the distance while attempting on remaining the same speed, then I would suggest going once a week to go further, while if you just want to be able to run longer, practice running longer. It'll get you there.
I like to do a mix between long runs, and multiple runs in one day. Today was one of those days. I went over to my cousin's house and ran 3.12 miles in 24:56 (7:58 min/mile average). After meeting up with him, we decided to go for a short run (with a little walking) and did 2.06 miles in 21:26 (10:23 min/mile average). I had a good time with my cousin, and after that, ran 3.03 miles home in 25:16 (8:18 min/mile average). They were nice runs and really helped put in a little bit. I think that later, I'll do one of those long runs in order to work my stamina. It really helps to switch out training styles so that your body wouldn't get accustomed to the training. Throwing new things around tends to balance the body pretty well. I need to work on my stamina, so I'll definitely do long runs, as well as multiple runs in one day. Every step counts.