I say you need to take the audience on a ride with ultra smooth mixing, or you can go for the combinations of tracks to make interesting clashes and doing tricks and so on.
You have to use tracks that complement each other, like blending something with a real basic but massive beat with something that has a real rapid fire but quite light one, or a real minimal track with a real melodic one, or tracks with real deep basslines so you can do switches without it being confusing in the midrange.
I often find that back2backs are good to learn this, as you have to match someone else's tracks with your own, so you got to think extra hard about how they'll go together