Achieving precise and reproducible stereotaxic injections is essential for accurate viral vector delivery. Backflow along the injection track can lead to off-target expression and compromise experimental outcomes. This protocol outlines a field-tested workflow that minimizes backflow through careful control of injection speed, needle geometry, and post-injection dwell time. We provide step-by-step instructions for mouse cortex and deep structures, including recommended coordinates and volume limits. By following these guidelines, researchers can achieve clean, localized expression with minimal tissue damage.