How to start using synths for sound design?
Today there are too many synths, hardware or software, with different characteristics. Also there are lot of types of synthesis to create sounds, some synths are using more than one of those types - subtractive, additive, fm etc.
I remember me when got my first synth and did not know where to start from. What are the various knobs doing? What will be the result if changing a parameter? How can I remember each change I made and liked it?
From the very beginning I wanted to create my own sounds. I do not know if it is mistake or not, I believe it is not. Nowadays besides of crafting my own sounds for my tracks I also enjoy to use ready presets (ok maybe with some tweaks to fit exactly to my projects). In the end someone who is listening to music is not going to judge the sound design capabilities, the point is to create nice music.
For both cases, the first thing that helps to connect the dots of a synth's function is to understand its signal flow (in most synths the signal flow is similar) and the purpose of each different sections throughout it.
In its most basic form we have the OSC module (where the sound is generating) flowing through the FILTER module (which usually cuts frequencies), then going to AMP Env (which uses an ADSR envelope to adjust the volume shape of the incoming signals) and final to Output. In between we could see some more modules like modulation stuff, effects, arpeggiators and many more.
Taking some time to read the manual of the synth software or hardware is helpful to see what is going on before we hear the final sounding result and how and when any of each module is affecting the signal.