I was always interested in music, I listened to what other DJs were doing. When I made this commitment, then I started to read, and there were various blogs by other DJs on the internet. A DJ from Finland, for instance, had a blog, Tanda of the Week. I was looking at what they were doing. And there were various DJs with their tandas on the internet, and there's stuff  you can read about how you build up a tanda.

I basically started copying them, and I think that would be my advice as well to other DJs who want to start DJing. You don't have to invent everything yourself. Basically, starting with copying what other people do is not the worst place to start. 

First, know the rules and then perhaps start thinking about breaking some of them 

I think I made every mistake in the book. No, but there are rules, and I think it's good if you start DJing to get to know them. 

Well, just like with other things, by the time you know what you're doing, then you can start thinking about perhaps breaking some of them.

But, just to name a few, I think a tanda should be coherent, and what does that mean?
The first record you put on, the first tango you play must be the indication of what the rest of the tanda is going to be. Let's say I put on very nice romantic Di Sarli, and perhaps you want to dance Di Sarli with a specific dance partner, and you would be very surprised if the next one would be very rhythmical, D'Arienzo for instance, because maybe you would prefer to dance D'Arienzo with someone else.

Those are extremes, of course, but it is important that the  first song gives you the idea of what kind of tanda is this going to be. Is it rhythmical? Is it melodical? Is it a more evolutionary style? Is it the '30s? Is it the '50s? Things like that. Let's say it's tanda for tangos. They should feel like they belong together somehow.