Anyone can take the training and exams offered by Google in their robust Academy for Ads learning center. You can gain a solid understanding of AdWords, DoubleClick, Analytics and more. From there you can become certified.
Once you are certified, you would begin the journey of marketing yourself for freelance work for businesses, or as a white label AdWords service provider to ad agencies, SEO companies and website developers. Or you could seek full time employment by someone.
Ultimately, the decision and path forward in personal and unique to you and not really something we can assist with here.
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