Syntorial is probably the best learning resource for subtractive synthesis, it takes you from complete beginner to advanced with an interactive course.
There are also a few good YouTube channels for learning sound design:
Mr Bill – Glitchy, granular sound design and out of this world ableton workflow.
ARTFX – Crazy awesome Neuro DNB sound design sessions.
SeamlessR – Known for his how to bass series.
Basic Wavez – Drum synthesis tutorials and more.
Au5 – check out his awesome drum synthesis tutorials.
Some artists stream their production sessions like Virtual Riot, and Kill The Noise.