Need Assistance In SEO WhiteHat and Lead Generation

Hello everyone,

Am now working on a Medical Writing Related services,
our services are
Clinical writing,
scientific writing,
manuscript editing
and so on.

My target country is USA, UK , Europe and AUS.
what will be the best platform for me to generate leads.

what kind of promotion and where can i post for full effectiveness???

Need Suggestions
Thanks in Advance.