Make time to give individual attention to students. If this is impossible due to the number of students, make time to work with students who have similar issues in small groups. After presenting a complicated lesson you want to assure students have understood, assign group work to the students and visit briefly with each group to assess their level of comprehension, or ask students to implement their new knowledge in an individual in-class assignment and walk around the room to see which students are having trouble getting started. If you have access to a computer lab, allowing students to do research or writing in class can also open an opportunity for you to give students more individualized attention.
Assess the needs of your students. If several students are having trouble with the same issue (such as comma placement or algebraic factoring), tutor them in small groups. If many students are making similar errors, it may be more time efficient to give another mini-lesson on the subject than to tutor those who are displaying difficulty. Identify students who continually excel in a particular subject in case you want to ask them to discuss with students at a later date (or to revisit your new class in the next term or year to explain their understanding to a new class of students).
Enlist others. Providing opportunities for student aids, volunteers (with an education background) or gifted students to teach mini-lessons can open time within the school day for you to work with students who are having difficulties. Alternately, allowing gifted students to tutor their classmates -- or, if you have the opportunity to "exchange" exceptional students with another teacher in a comparable class -- may allow you to incorporate such tutoring when you don't have time to actually work with students individually. Student aids and volunteers may be able to tutor during class so other students do not have to give up their own study-time. Education majors at local colleges may be looking for opportunities to work one-on-one with students, and are often happy to provide such services for free, to obtain recommendations, service-learning credit or an entry on their co-curricular transcripts.
Evaluate the progress you're making. Keep note of what methods you are using and, qualitatively, which work best. This information may be helpful for other teachers who want to include tutoring in their classrooms. Maintain detailed records to reflect whether or not tutoring during the school day is making a difference in students' understanding, attitude, assignment completion and test scores. If you see there is a positive difference, record the type of difference and include any relevant statistics (such as score comparison). If you find a particularly successful tutoring regime, you may be able to secure funding (within your department, school or school district) or obtain a grant to hire student aids or purchase additional materials. This information is also helpful to show during performance evaluations and when applying for other positions.