In terms of speaking exams, the most cliché answer is practice, practice and practice! The advice that used to help me a lot when revising for a speaking exam is to record yourself speaking and then listening back to it. Furthermore, it is also important to know a range of vocabularies and to remember at least a couple of phrases for every topic. For instance, for the speaking exam (AQA Paper) it is split into 3 sections; Role play (2 min), Photo card (3min) and General conversation (5-7min at Higher). The fact that the General conversation is also split into 3 main themes (1.Identity and culture, 2. Current and future study and employment and 3. Local, national, international and global areas of interest), it would definitely be a great idea to think of a lot of phrases and vocabularies relating to these themes. In that way, when faced with any questions you will already be a step ahead!
Identity and culture Current and future study and employment