Introduce the concept first. The concept is the basis to everything and it should serve as a platform on which you will build on the lesson. Make the concept as interesting and as applicable to everyday life as possible, with the help of visual aids such as graphs and tables. Explain everything slowly and in detail.
Begin the lesson with basic problem examples of the lesson. Solve the problems on the board yourself. While you are solving the problems, explain each step you are taking, especially if you can call upon lessons already learned and apply them to the current work. Back up every step you make with the concept as repetition is key to understanding. After you are finished, give the students a chance to ask you questions and clear up anything they don't understand.
Write one or two problems on the blackboard and let the students to solve them on their own in their notebooks. Tell them to call you over if they have any questions. Walk around the class to find students who are having difficulties and help them solve the problems.
Call some students to the board one at a time to solve some more problems with them. If you haven't done so yet, now is the time to introduce the more complex math problems that use the concept you are teaching to the students. Tell the rest of the class to write down the problems in their notebooks and solve them on their own to practice the concept and master it through repetition.