How to distinguish mushrooms?

Now it's autumn, time for mushrooms! But when talking about mushroom hunt, distinguishing them is very important. Of course, if you don't have a lot of experience, it's better not to take questionable mushrooms. But what if you decided to take some type and just see if it's eatable, but you cannot understand the difference by the description or photos given in internet? Recently we went to the nearby forest, and we fond some mushrooms that seemed eatable. As we were not sure about them, we put them in a separate bag and brought them home to find them in the internet. And we found 2 types of mushrooms, which both looked similar to ones we found. One of them was poisonous and the other one was edible. We decided to through them away, but before we did, we noticed that we didn't check one parameter. Have you ever read in the description of a mushroom: "Color of the spores"? And you asked yourself: "How do I know the color of the spores? Isn't it something you see in laboratories?" Well, actually, there is a very easy way to know the color of the spores of a mushroom. All you need is a peace of white paper and an old (overgrown) mushroom. You cut the stem of the old mushroom and put the cap on the paper, gills down, like shown in the video below. Probably you'll have to tap the mushroom a bit.