I recommend the following books:
"Learning Teaching" - Scrivener
"Grammar for English Teachers" - Swan
"Grammar in Use" - Murphy
"500 Activities for the Primary Classroom" - Read
"Discover English" - Borlitho & Tomlinson
There is a post on my blog about
Grammar Books. For further development;
1. Organise teacher workshops
2. Attend teacher workshops
3. Join IATEFL (
IATEFL - International Association of Teachers of English as a Foreign Language)
4. Do the CELTA/TEFL course
5. Observe other teachers
6. Teachers observe you
7. Ask for feedback from students
8. Push your boundaries