Signs of bad books for English language are: an abundance of images, which often constitute up to 90% of space on the page, a huge font, futile exercise. However, the main weakness of the proposed literature is the lack of understanding of the authors of serious grammatical realities native of the English language on the one hand, and absolute ignorance of the authors of the Russian language. This, in turn, deprives the possibility of effectively studying English grammar in comparison with Russian, and leads to English / American pronunciation and develop the ability to understand speech at the hearing. With a huge supply of various 'miraculous' production of English pronunciation courses, in reality 99% of them – no more than a desire to earn on the sale of the course, ie, You buy some cd and booklets, pay for it a lot of money, and the output – again zero. Therefore, after several fruitless attempts to learn English, one comes to the realization that he needed help of a professional teacher or tutor in English. Realizing the lack of progress in an absolutely independent study of English, one begins to look or English courses or private tutoring in English.
Here there are several pitfalls. I would not recommend to choose 'untwisted' courses and schools. Not because I am against them as my competitors, but only because I am very familiar with the 'kitchen' of such organizations. Imagine yourself in the place the owner of such a school. Your vested interest – to get as much profit, therefore, you'll optimize their costs, and means to pay your teachers – at least.