The more time you spend running, the more you’ll learn about the sport.
As you become more involved and really get to know what it’s like to be a part of the running community, you’ll likely hear advice like, “don’t run every single day,” “your cadence should be about 180 steps per minute,” “always wave when you pass another runner on the road,” and “make sure to include foam rolling in your routine.”
In general, for many runners these are good rules to follow, but the most important thing you'll ever learn about this sport is that the there really aren't any concrete rules; none of the above is mandatory because it might not be a strategy that works well for you (well except for the waving thing, maybe).
Any “rule” you learn about running, should more so be considered a guideline, because to be the best runner that you can be you'll have to spend some time experimenting with a variety of different techniques before you find which work best for you.
From one runner to the next, we all have different goals and we all have different needs. What works well for your friend might not be the best option for you.
Take marathon training for example, some runners might get the most benefit from a training plan like the Hanson Method, which prescribes six running workouts per week, while another runner of the same level and capability might find more success with something like the FIRST Training Program, which calls for only three days of running per week.
Both strategies have worked for plenty of runners, which goes to show that there's no one "right" way to run—whether you’re training for a marathon or working towards finishing your first 5k.
Of course, all of this shouldn’t downplay the importance of direction. If you want to become a better runner you’ll need to set goals and come up with a strategic plan that will help you reach them. It’s just important to remember that you (or a coach) will have to put in some extra work to come up with a method that includes the techniques and tools that best serve your very unique needs.
So, never let anyone tell you that you’re doing it wrong. Because while you’ll certainly make mistakes, there will always be more than one “right” way; it might just take some time until you figure out what it is.