An informed recommendation is the best recommendation.
Planning in itself can’t increase the chances of getting a great teacher recommendation. Your performance in their class and how they observe you using your new found knowledge outside of the context in which it was gained in their class are the things that typically lead to a great recommendation. But there are steps that you can take that will ensure that when the teacher most capable of doing this task for you accepts your invitation to do this, they are equipped to do it efficiently and effectively.
First, you should identify the teacher based on the academic area to which you will apply. For example, your accounting teacher is probably more appropriate than your music theory teacher to write a recommendation for you if you are applying to major in accounting.
Second, when you ask the teacher, be prepared with a great “one minute elevator” speech. In other words, you have one minute to ask the teacher to write the recommendation but it must also be convincing and genuine. When you ask, it is important to explain why you have chosen them and what you would hope they would discuss in the recommendation. This helps to frame in their mind the context of the recommendation and their ability to achieve your request without putting too much burden on their workload. Remember, good and popular teachers tend to be asked a lot and at some point they have to start saying no. If you currently have them for a class it makes asking all the easier because they are currently familiar with your work.
Third, be prepared to give the teacher a copy of the curriculum for your major from the school to which you will apply as well as any instructions for them to follow in preparing the letter. Some schools are seeking very specific information from teachers about their future students.
Fourth, make a list of the attributes or accomplishments that you have achieved in high school and especially bring their attention to the ones which they have specific knowledge about your abilities.
Fifth, it is always a good idea to give them an example of your work and especially well done assignments that you had completed for them. This will help to remind them about the quality of your work and other attributes that they have associated with you since they have gotten to know you.
Sixth, provide them with a copy of your future career and intended major goals. They need to better understand where you see yourself going and how this school may be the right place to help you accomplish those goals.
Next, remember to provide them with a stamped and addressed envelope if it is to be mailed to your school. Most importantly, remember to thank them for completing the letter and follow up with them about the final outcome of your applications. I am sure they would like to know how the end of your application story turns out.