1. Follow instruction and Answer all the question .For Example if any questions required "Answer any three with four words" never answer the questions with five words.
2. Never Assume that you know the answer read passage carefully .For example, the question is "Does smoking cause cancer" and your mind say "Yes" but the passage says "No", then "No" is the correct answer.
3. Properly read whole passages.Read the whole passage carefully.Those passages are not meant to be read.It is enough to scan through the text, noticing what the text is about and what the purpose of each paragraph is.After getting familiar with the passage, it is the time to read questions and look for answers.
4. Never work with more than one passage at a time.No one will tell you to stop working on the current task and to move forward to next one.So, in worst case scenario, you could spend all the time working on just one passage, when there are 3 more to go.
5. Do not waste your time with hard question.Waste a lot of time on one hard question .All IELTS questions are of different difficulty.It is wrong to assume that every next question will be harder than previous one.This is why getting stuck on one hard question is a bad idea.By moving forward to some easier questions you could win points,which otherwise would be lost.