As Oren Klaff said...you can't steal it, you can't find it, you can't buy it...you have to earn it.[0]

Courses and books give you tool. For sharpening, you have to use it daily.

Good resources about "tools":

> I'd Rather Die! Public Speaking Survival Skills by Robert Scanlon.[1]

> MIT OWC - Rethoric [2]

> Oren Klaff - How To Pitch Anything (LondonReal) [0]

> (not exactly about speaking but suitable for speak preparation) Technical communication by Mike Markel [3]

[0] https://www.youtube.com/watch?v=WxwTn_f5yaI

[1] https://goo.gl/zv2DOY

[2] https://goo.gl/oJ4lRL

[3] https://goo.gl/AxS1Pc

Edit: Formatting