"Where's the best place to acquire customers for my startup?"

Well, some places to consider:

• Google Search
• Instagram
• Facebook
• Quora
• Amazon
• Google Display
• App Store
• Pinterest
• Snapchat
• YouTube
• SEO
• LinkedIn
• Affiliates
• UGC
• Influencers
• Direct mail
• Physical ads
• Share-worthy content
• Network effects
• Referrals
• Bing
• Sales
• Content aggregators
• Speaking and events
• PR
• TV/print/radio
• Community
• More...