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Assuming you are about to build career in digital marketing. Start learning basic concepts available on youtube. Mind it you have to learn basics not tips. Thousands of digital marketer make videos to share tips in order to get views. Don't watch those videos. Watch tutorial videos which explain concepts and how it works. (7 days)
There are 3 main modules in digital marketing SEO (Search engine optimization), SEM (Search engine Marketing), SMM (Social media marketing). Take one topic for example SEO. Start exploring on internet. Learn basic concepts. Once you are done with basic concepts of one topic start working on it. (30 days)
Start reading blogs related to digital marketing which shares insights. You will be able to develop strategies. Now go for any online certification at first. Start internship with any good agency. May be they will not pay you. But In long run brand tag is necessary. (6 months to 1 year). Now you have learned a lot, practically implemented it in internship. Learned new things from companies. Start applying for jobs. Trust me if you are skilled and know your work. Getting job after internship is easy. Here you have to make decision you have to build your own agency, Become freelancer, or continue your job. Job is mandatory for few years as you will learn how business is done in agencies. How they get client, how they retain client. How they charge their client and many more stuffs. Then Do whatever you want to do.