Fm synthesis is really fantastic. There's a history on it some where....But i know you can generate many natural sounding tones and timbres with it.

that being said, it's also a pain in the ass to use effectively and effeciently.

Wikipedia

Out side of that, it's just changing the waveform to what ever characteristic you want. I know you can get some really nasty basses out of it, and some pretty ok sounding leads. It's typically described as harsh, and very hard to control if you're using it in a polyphonic  way. but that lack of control will lead you to interesting effects that you may utilize for music. But for music's sake, it's just tough to control.

Start with just 2 operators.

Also, start with simple intervals. Say you're in FM8.

Click File -> New and you'll get a blank patch with just operator F sending a sine wave to the master out at full amplitude.

Then turn on just operator E modulating operator F's frequency... start with operator E's frequency ratio 1.0 (IE same frequency as operator F)... turn up and down the amount it modulates operator F and listen to the harmonics.

Then play with operator E's ratio: experiment with 2.0, 3.0, 4.0... and 1.5 & 2.5 (I love 1.5).

Then, change operator E's envelope so it's fast attack and medium decay to zero. Get the envelope and the ratio right and you'll get some tasty FM bass sounds... or Tchami/Heldens (I think) lead sounds. Certainly something that has a place in that sound palette anyway.

To be honest, my favourite FM basses are 2-operator patches, so you could usefully spend a few sessions just on 2 operators.

Get super comfortable with that... and then... well, you could cut back to 1 operator and experiment with self-modulation? Or you could introduce operator D, and see what happens when you modulate F from D & E at the same time - or what happens when D modulates E and E modulates F. That breaks the limit of my experience, but once you've learnt 2-op FM you'll have a much better feeling for how FM works overall.

http://www.amazon.com/How-Make-Noise-Frequency-Modulation-ebook/dp/B008H7CEQG

I highly recommend buying this book to understand some of the basics about FM synthesis. It's a great way to understand how deep the modulation and parameters you can shape to have a really dynamic sound. It's only like $3.

I also hope I don't get kicked off the forum for really liking this book.

just a heads up as far as FM synthesis goes for dubstep, unless you have waveforms outside of the standard square, saw, sine, and triangle, you're not going to get anything worthwhile

this is the one single type of synth, where i just stare blankly at the synth, wondering what is going on.
i get the fact you can use one osc to modulate another. thing is it all sounds so boring and over the top geeky.
but then i hear some of the sounds people make, and it makes me want to know. so im gonna try.

not gonna buy any more synths, and not using "dubious" downloads anymore, but i did get octopus in a sale recently. if anyone knows it, is it good enough to get nice acoustic-type sounds out of it?
if its gonna be my only fm synth, is it worth even bothering?
might try some basses too, if its considered an ok synth