Tray Balancing
I love tray balancing. Actually I love to put anything on my head and try to balance it, but a tray with fire on your head! Love it. Not only does it get a great response from your audience, but it really makes you work hard on isolation, and I love good isolation.
I haven't seen many tray balancing dances lately. I'm not sure if it's "out of fashion" or if I'm not following the right dancers or using the right search terms. People seem to be more partial to the sword and the shamadans at the moment.
A few notes about balancing trays (with or without fire).
I use a few drops of wax on the underside to give it some traction on my hair. Your hair shouldn't be silky clean either. A little bit of dirt can help to hold it in place and not slide like on super clean hair. I've seen some people glue velcro on the underside, but I don't see how that would really help much more than a few drops of wax. Plus, when you take the tray off your head your hair sticks to the velcro ruining the effect.
You don't have to keep the tray on your head for the whole dance. You can put it on and take it off as you please. In fact this shows your audience that you aren't using any tricks to balance and that it is purely your talent and hard work keep it on your head.
Balance out the items on the tray. You don't want a lopsided tray. That's nearly impossible to balance nicely. If you have a tea tray, chances are the cups and pot have ridges they fit into. If you are placing candles on, you need to make sure their weight is evenly distributed.
If you have candles ...
Be careful around draping.
Another trick I've discovered is to insert magic candles into pillar candles to make them more wind resistant. I pull the candle's wick out, drill a small hole where the wick was and put a magic candle (the ones that can't blow out, they just reignite) inside. It's not a solid guarantee that they won't blow out in a strong gust, but they are definitely more resistant.
This video is of Vivi Belly Dance dancing to Yearning (this seems to be a very popular song for tray balancing).