1) Deepen your shots. Almost every scene should have at least three things in different light intensity and should occur on at least three planes. The close-up against a wall is the hallmark of cheap filmmaking. Don’t rely too heavily on such simplistic shots. Create a whole scene.
2) Move the camera. If you find yourself panning and tilting a lot… don’t. Rent/borrow/make a crummy dolly and use it as best you can. Jib shots are nice, but dolly is so easy and cheap, while providing (in my opinion) the coolest effect you can give your image. For bonus points, point the dolly at your subject and creep forward smoothly during intense dialog.
3) Avoided handheld unless you are really damn good at it, or if you don’t have enough time to do it properly. Too many filmmakers go for the “handheld look” and achieve the “hopeless amateur look.” Steadicam stand-ins like the Glidecam are readily available if you must run around. You can always add camera shake in post if you want your images to breathe.
4) Learn how to use backlight. I’m assuming a filmmaker has taught herself to light, but maybe you do or do not have money or access to lights. Big, soft sources of light (windows, for example) contribute to gorgeous compositions. You just need a backlight. Get something shining on the back of your actors head, or, depending on angle, on the side of their face, and you will get a three dimensional shot. Even a phone light is better than nothing. Seriously.
5) Decrease the depth of your focus field. If you can control your aperture (as on a cinema camera or DSLR, this means making your aperture big (smaller number=bigger aperture). If you are outside you may need a neutral density filter to reduce the amount of light entering the lens. If you can’t control your aperture, an ND filter is your only hope of convincing the camera to open up. Camcorders often have very small sensors, which means that their depth of field is always very long. That’s why they give you home video results. That being said, don’t be one of those assholes that shoots everything close up with the background blown out. Use this principle according to principle #1.
6) Block your actors creatively. If you always shoot dead on or at profile, you’re going to look like the news. Get at an angle, under them, etc. Don’t line them up with each other. Move them through your three dimensional space. Have them transition from soft to direct light. Much thought goes into this on serious films; plan it out and move through it on set. Be open to resituating your actors if the light speaks to you.
Practice, practice, practice. Get really good at visualizing and executing shots, and these principles will become habit.