You need to make decisions very quickly, as that isn't a lot of time. So you really can't spend time trying to decide if one method or word is better than another. With so little time, you will need to hit the ground running really quickly, so you might need to tweak the time and go with a shorter amount of time to plan. 1/4 of 30 minutes is 7 1/2 minutes. You might need to shorten that to 5 just so you can get the words out. You might also need to scrap the proofreading step as you'll need the minutes.
Keep thinking about how one sentence connects to the next one, and how one idea leads to the next. That's about the best I can tell you, as that is a rather short amount of time, particularly for a person who is not a native speaker.