I usually recommend this grammar book for LEVEL 1: beginners or those who have studied English but don't remember the most basic grammar items. It shows examples in short texts, there's an explanation of the rules and graded exercises, from simple to more complicated. Buy one with key so that you can correct your mistakes.
Learning English grammar is a question of patience and practice and more patience and more practice because you learn, forget, remember, forget, practice, remember.....a never ending story! but it keeps your English alive!