Hi Stefan,
Interesting post
When i first started out coaching, a very good friend of mine (a very successful business coach) gave me some advice that proved invaluable to me.
That advice was - Niche, Niche, Niche.....and then Niche some more !
I already ran ( and still run) a successful business in the thrill a minute world of Health & Safety. I wanted to coach anybody, in any field. But i took my friends advice and only coached people in the same situation that i had been in (Safety Consultants).....this gave me the confidence to grow my coaching practice and now i do indeed coach anybody from any field.
In short, my advice to you would be to niche your coaching practice....initially anyway.
And dont apologise about your english...my family have been speaking it for hundreds of years, and i stiil aint got it right !

Cheers,
Mark