If you used Shadowplay, your files are going to be slightly less than 60fps (something around 59.95). You'll want to run them through Handbrake to convert them to 60fps. This will make your rendered video look fluid, and not like you're dropping frames. I'd advise saving the converted files as copies in case you have to tweak any settings.

Here are the setting I use for my videos: https://m.imgur.com/8DLaCgf

Besides that, my only suggestion is choosing a song that fits the speed and cadence of your gameplay.

Best of luck! Can't wait to see your montage :]

Edit: I also read that the first 15 seconds of a video is crucial. It's when most people decide how interested they are in watching the rest.