Custom resolution and custom frame rate

Hey everyone,
I'm very new to final cut pro. I've just started making some videos, but I'm a bit confused about setting custom resolution and custom frame rate. I film my footage at 720p - 60fps and sometimes1080p - 30fps. If i want to use 720p - 60fps and 1080p - 30fps clips in the same video what would be the best resolution and frame rate to use?
Thanks,
Charlie

there's no best:
1080 - preserves your fullHD materials res, but blows up your 720 material = loss of quality
30fps vs 60fps - same story.

if you want to use your 60fps for slowmo, you should set your project to 30. And if you like to reframe your 1080 material, you should set the project to 720 ...

for sure, a higher framerrate or higher res than recorded doesn't add any 'quality' to your material........

And, Welcome Charlie, to fcp.co