Are you using LUTs? That's not possible to use in Express version of HitFilm. You're going to need the colorist add on.
Workflow? Depends on your style/preference. I can tell you mine, I guess, which allows for the highest quality possible until delivery.
1. Shoot in a fat profile (if gaming then this doesn't mean anything to you)
2. Transcode the files to an intermediate codec, in my case DNxHD (175)
3. Import, trim and edit in Resolve
4. Color correct and color grade in Resolve (if games you can only color grade, as they're already corrected)
5. Export as a uncompressed AVI file, if my project need additonal work in a different program. Otherwise I export to H.264 MP4 at a high bitrate
7. Transcode the AVI file to DNxHD (175)
8. Import the file to a different program
9. Repeat steps as many times as I find necessary, incase I need to go back. That's why I always stick to uncompressed AVI, to avoid compression artifacts.
The reason I use DNxHD, is because it's an intermediate codec, which is specifically made for editing, so unlike other codecs there won't be any obvious hiccups when playing back, as well as much smaller file sizes, with no quality loss from uncompressed AVI. For YouTube work, just export at a high bitrate in H.264 MP4, YouTube is going to take the file and ruin it anyways during upload. None of these things are rules, just my workflow.
I use MPEG Streamclip to do the transcoding: http://www.squared5.com/
I require the DNxHD codec:
http://www.videohelp.com/software/Avid-DNxHD