To grow marijuana indoors successfully, provide ideal conditions. Use quality grow lights, maintain temperatures of 70-85°F (21-29°C) during the day, control humidity (40-70% in vegetative stage, 40-50% in flowering), ensure proper ventilation, adjust pH levels (5.8-6.5), use appropriate nutrients, water when the top inch of soil is dry, choose a suitable growing medium, and maintain proper light schedules (18-24 hours of light in vegetative, 12/12 in flowering).