"We'll fix it in post."

No you won't. Whether the problem is lighting, sound, acting, the perspective of shots, film speed, there is no such thing as "fixing it in post." Get it right the first time.

Filming will be a lot easier if you have spend time and thought on the planning process.

Tips:

• Get a variety of shot sizes.
• As you set up each shot, check the frame, lighting, focus, and sound.
• Get all the footage you need; coverage means making sure you have all the shots you need for a scene.
• Camera movement should be used for a purpose, not just to avoid editing. When movement is necessary, make sure the movement is smooth (use a dolly such as a wheelchair or skateboard) and only in one direction.
• The shot duration should be a bit longer than what you want in the final film: editing down shots is much easier than re-shooting.
• Shot/reverse/shot is a common technique for filming dialogue. Begin with a "master shot" that shows both characters, film again with a close-up of one character, and again with a close-up of the other character. Film other shots (extreme close-ups or mid shots) as necessary.
• The 180 degree rule means that characters should maintain the same left/right relationship to one another in a scene. If the camera crosses the 180 degree line, the scene will seem awkward and confusing to the viewer.