To successfully answer IELTS True False not Given questions and Yes No Not Given questions, you can use exactly the same technique. The difference is that Yes No Not Given texts are based on the writers opinion, whereas TFNG texts are based on facts.
Take at look at the graphic below for some ideas to help you.
Techniques and tips for IELTS Reading True False Not Given questions.
The reading section in IELTS contains many types of questions and a lot of IELTS students have problems with two types of questions, True False Not Given and Yes No Not Given. Surprisingly, once you understand the techniques and practice this type of question then you will realise they are a lot easier than you think. However, you really do need to have good vocabulary to get a good score here.
The IELTS reading test actually tests your vocabulary such as synonyms, collocations and paraphrasing. TFNG questions are based on factual statements in the text and there are some tips I will outline below.