In my view learning English grammar in the following sequence ensures firm solid thorough knowledge of English grammar:
1. Read a short clear easily understandable explanation of a grammar rule.
2. Study several practical usage examples (sentences) illustrating that particular grammar rule. Check yourself whether you have mastered the examples.
3. Do several exercises for that rule with communicative content (with sentences that most likely can be used in real life situations).
Grammar exercises that contain dialogues, interrogative and statement (or narrative) sentences on everyday topics, thematic texts and narrative stories are especially effective for mastering grammatical structures.
Grammar practice should also include exercises in listening comprehension and speaking, not just in reading and writing.
Grammar exercises must help learners not only form correct sentences, but also use them correctly in context in real life situations. Contrastive and contextualised exercises give practice in form, meaning and use.
It is very important to learners for practising English grammar on their own that there are answers provided to the exercises (the key) in the grammar practice book for self-check.