I don't have previous customers/testimonials, willing to give a discount if necessary. How do I know which companies need content creation (blog posts, copywriting, whitepapers, email marketing) and don't already have an in house writer?
Hi - many freelance gig economy marketplaces have customers publishing such requirements. Register on them and make compelling pitches. Examples are fiverr, upwork, freelancer, contently, clarity(!), and dozens others. Be ready to negotiate first few at very competitive rates or payment only on acceptance basis.
Once you have some successes you should make a 3-6-9 month revenue plan.
Hope this helps. All the best.