Start with the 100 most common words.
Take this list from Wikipedia as a first step, but be mindful, that the first 100 most popular words consist largely of prepositions, conjunctions, articles and different forms of pronouns. These are very useful to learn, but they are just a first step in extending your vocabulary and adding to your ability to learn English, as the choice is fairly limited for creating your first phrases and sentences. To be precise, your 100 most common words in English are: 25 nouns, 25 verbs, 25 adjectives, and the other words. Next step extend your 100 most common words in English and select 50 more of the most common nouns, 25 more of the most common verbs more and 10 more of the most common adjectives. This vocabulary will be sufficient for the first stage of your learning English.