Mixing in key - An help to build a smooth set

So i already posted here some tutorials on Virtual DJ, that is a DJ Software that allows you to play musics and mix them like a professional DJ.
So now it's time to talk about another important topic, key, that will be very helpfull when you start creating you set. To have a very smooth mix between to songs, besides the bmp (beats per minute) that must be similar (you already noticed that), they should have a similar key because because it will be easier to mix and will sound better most of the times.

I will try to do a series of tutorial soon on how to begin constructing your mixes and your sets but for now i leave here some videos that explain the importance of the mixing in key. Those videos are from DJ Tutor (ellaskins youtube channel).

Mixing in key - Part 2

Mixing in key - Part 3

Mixing in key - Part 4