Standing ground / debating points advice

[RupertSquare]

I'm terrible at being able to stand my ground on subjects ranging from who last put the bins out definitely me to the ethics of population growth (and other not so high brow topics).
I KNOW on a few subjects that I have enough experience and knowledge to be correct on something but I usually get flustered and end up saying something silly or even welling up. Im usually better in the written word because I have time and can edit!
I know there are lots of brilliant communicators on here, as I see so many brilliantly thought out posts but PLEASE can anyone help me in improving my (especially spoken but written too) ability to make a convincing point and I suppose argue it effectively?? Are there tutorials or people I should read?

[RupertSquare]

Hopeful bump

[ThickFast]

I’d like to know too.

[MotherForkinShirtBalls]

It's so frustrating...I usually end up crying too.