Teaching English as a Second or Foreign Language
Marianne Celce-Murcia
The third edition of this great book offers theoretical and practical advice. 

Techniques and Principles in Language Teaching
Diane Larson-Freeman
Teaching techniques in English as a Second Language.

Teach Yourself Teaching English as a Foreign/Second Language
David Riddell
A guide to teaching English, classroom management, lesson planning,using course books, job hunting, and career development.

Teach Yourself Teaching English as a Foreign/Second Language One to One
Jane Downman, John Shepheard
A practical, concise guide brimming with new ideas for motivating your students.