You can use whatever candle you want. I also practiced on small lamps, such as LEDs, when candle wasn't available due to circumstances. You need light source to leave an imprint in your vision, on which you can work later. It should go without saying that you shouldn't look at something too powerful which can hurt your eyes.
That's why candle flame is the best for this. It is of ideal shape and luminosity.
-Larissa