Hey Artificial,
If you search "audio for film" on YouTube, there are all kinds of tutorials and "audio 101" lessons - Watch all of them because everyone will have different advice and it's good to soak everything in, and then you'll filter what you need.
I can testify that the RODE VideoMic is capable of getting you some good sound for your film, as long as you keep a few things in mind...
As you know, most cameras' onboard audio is atrocious, and having ANY mic is probably better than having no mic. For the VideoMic, I use a
Zoom H1 recorded which you can pickup for under $100. Then you can purchase a
high-class high-capacity microSD card on Amazon for under $20 and you can record all day without ever worrying about running out of space. Even the
cheapest RODE Boompoles work great.
With this combo, you can get great audio. Most people use a clapboard to sync each shot. I don't...instead, I just sync my camera's audio with my recorded audio in post, then delete the camera's audio. It's not the most graceful route, but it works for me.
A few things to remember:
The VideoMic has small configurable decibel switches located in the battery enclosure - Have you seen them? Your manual should tell you about them and offer a diagram. You can set the mic to record at -20, -10, or 0 decibels (I think?). Since I have the mic plugged into my Zoom H1 which controls the input digitally, I leave the mic's setting to 0 decibels, so I know I am getting the full possible input from the mic itself. If my actors are too loud and it's clipping, I just turn the input down on the H1.
On the VideoMic, there is also a switch with an image that looks something like this: "/-|" (maybe not exactly like that, but you get the point). This is for when you use the mic with a boom pole. There will always be a little bit of rumble from whoever is handling the boom pole, and switching the mic to this option will bypass some of those low frequencies so they don't interfere with the audio you intend to record.
You'll also want a good pair of headphones to plug into your recorder so you (or your sound guy) can monitor everything that the mic is picking up. They don't have to be anything fancy, but you probably want something padded and sound-canceling so you can focus only on what is going into the recorder.
As for ambient noises, background, and sound effects, you'll usually want to record these kinds of sounds separately from what you record on set, or find libraries with the sounds you need. This is called "foley" in the film business. For punches, record yourself hitting a piece of cabbage or a phonebook. For footsteps, record yourself walking in place in the grass, on gravel, sand, etc. For monster noises, record a dog barking or a pig squealing, slow it down, double it, reverse it, and add reverb, and you'll get some creepy sounding stuff! For everything else, just do a Google search for "______ sound effect" and you'll find something you can work with or some inspiration.
Audio is never an exact science. It is going to always require testing and troubleshooting for almost every shot, but it's worth it to do it right. They say audio is the better half of video, and it's true. Your audio doesn't just compliment what's on screen, it has the potential to make it explode off the screen!
Good luck with all your projects! Hope this info was helpful, and feel free to pm me with questions. I'm no pro, but I'll be whatever help I can to you.
-Matt