I am an absolute beginner and trying to learn by using Ableton Live. I would like to produce downtempo and chill-out but at this point I am open to any kind of information that can teach me. I want to start learning sound synthesis and thinking of trying FM8 since I heard so much good things about it. Is beginning to learn with FM8 is a good investment of my time at this stage or should I begin with something simpler or different? Can I apply the techniques I learn in FM8? For e.g. if I tried and learn all of the information listed on synth secrets , will I be able to apply these in FM8 or will I need to look for specific kind of guides?
I love FM synthesis, but it is generally a bit on the esoteric side. FM8 is probably one of the easier FM synths to learn. But even after mastering it, you will still have a hard time achieving a particular sound that you want. FM8 is great for making weird bloopy, bleepy, buzzy, metallic sounds. And basses.
If you don't have it already, I'd recommend upgrading to Live Suite, and working with the synths you get there. Downtempo / chillout is more about great sample manipulation than crazy synthesis, so you probably don't need much more than that.
Although I have FM8 and am comfortable working with it, I tend to gravitate towards Ableton's Operator or one of my hardware FM boxes. There is something about a pushbutton interface that works really well for FM, so I've managed to get a lot of use out of my TG77.
If you were to go the Native Instruments route, buying one of the Komplete packages is usually a much better deal than individual synths. So if you only want FM8, I would wait until you have an interest in Reaktor or Massive as well. Then just get Komplete.
If you want to work though the Synth Secrets (which is an excellent resource, by the way), then a modular environment like Reaktor, Pure Data (which is free), Max/MSP or an actual modular synth is the best way to go. You can get a lot out of a fixed-function softsynth or hardware synth, but modular will give you the greatest flexibility.
For others wondering if they should start with FM8 or another FM synth: If you are just curious about synthesis and want to mess around and see quick results then start with an (possibly virtual) analog style subtractive synth instead. You can make a lot of cool sounds that way, and the results are easy and intuitive. If you are really dedicated to learning about synthesis, and have the motivation to see things through, then there is no reason not to start with FM. Particularly if you find a DX7 at a garage sale for $50 (or any of Yamaha's other synths, from the 4-op TX81z, through the SY99 and on to the FS1r). It won't be as easy to learn FM, but it also won't be any easier later. FM is just obtuse and the only way to learn it is to get your hands dirty. So, if circumstances present themselves, feel free to start with FM. Be prepared to dedicate yourself, and don't go out of your way unless you are ready.