How do I know when to put the accent in a word?

There are rules to know whether you have to put the accent or not. If a word is "Aguda", the tone will be stronger on the last syllable of the word. The vowel in this syllable will have an accent if the last letter is either an "s", an "n" or a vowel. Examples: Atención, Compás, Colibrí. If a word is "llana", the stronger tone will be on the second-to-last syllable and they will have an accent if the last letter of the word is not "n", "s", or a vowel. Examples: Árbol, Lápiz. When the words are "Esdrújulas" the strongest tone is on the third-to-last syllable. These ALWAYS have an accent. Examples: Plástico, Médico, Rectángulo, Párrafo. Words that are "Sobreesdrújulas" have the accent in the syllable before the esdrújulas and ALWAYS have an accent. Examples: Préstaselo, Cómpraselo.