You shouldn't aim for the easiest certifications to obtain so much as ones that will support your career goals. With proper preparation and education, you can tackle even more challenging certifications. That said, certifications that are generally considered easy to obtain include, information technology certifications, language-based certifications (such as ESL and TOEFL, depending on the language), certifications within healthcare, notary certifications, and some software and government certifications. But what's easy for you may be more difficult for someone else.