Reddit mentions of The Complete Guide to Game Audio, Second Edition: For Composers, Musicians, Sound Designers, Game Developers (Gama Network Series)

You should not agree to an hourly rate as a freelance audio producer. You should have a per minute of audio rate. Rates tend to be all over the place but depending on the project you can safely ask for $30 per minute of audio. I usually ask for $50-100 per minute of audio. I highly suggest reading entirely through Game Audio by Aaron Marks. You should also write royalties into your contract. Usually a percentage of profits. 1-5% for total audio production (one person) is probably fine.

Tl;dr Only agree to hourly rates if you are hired as an in-house audio producer.

I download short films on archive.org and mute the sound, and practice scoring to them.

I also wasn't finding much work in film, so I started writing music for indie video game developers. Winifred Phillip's book has been very useful to me (it's a big picture kind of understanding with plenty of practical advice) and I just started reading Aaron Marks' book which has some good stuff in it.

Someone also recently told me about scorbit (started by Berklee I think), which I personally haven't used much but have heard good things. You can set up a free account with them which is nice.

YouTube is filled with great (and shitty) advice. Honestly, I have more sources than I have time to explore anymore, so I'm just picking a few, and doing the hell out of them.

Also, the TigSource forums are great!

The book, The Complete Guide to Game Audio (For Composers, Musicians, Sound Designers, and Game Developers) includes a sample

• non-disclosure agreement
  
• talent release (performers paid by you to use their performance as your "work")
  
• work-for-hire agreement
  
• audio development agreement (based on Tommy Tallarico's standard contract), and
  
• professional services agreement (basically a generic agreement you could expect to receive from a larger studio).
  
  I think the DVD that comes with the book includes PDFs of these contracts, but I'm not sure, as mine is lost in the stacks somewhere.

There are very good books on Amazon which might get you started on game audio. Some links :

Game Sound: An Introduction to the History, Theory, and Practice of Video Game Music and Sound Design
A Composer's Guide to Game Music
The Complete Guide to Game Audio: For Composers, Musicians, Sound Designers, Game Developers

About the audio engines (audio middleware), the two big ones are FMOD and Wise (when the studio is not using its own middleware). There are some tutorials on Youtube which might get you started on that. It's essential to know the basics of sound integration (I mean how to use FMOD/Wise with game engines) if you want to work in video games.

Also, come join us over at /r/gameaudio