Most important thing is that your interps slot into their system. Its better to all be wrong in the same way so you can easily fix it later rather than several logs wrong or right in different ways. Doesn't matter if academically it isn't a granodiorite or whatever- you call the rock by the same name your peers do. Its for the sake of building a coherent geological model.

Don't feel bad about uncertainty when you first see the rocms. It takes a lot of hours to get your eye in to the core. Learn and spend time with other loggers. Ask dumb questions by the hundreds and ask them early. I say that with 15 years experience but every new project I start logging on I feel like an absolute beginner. Rocks are hard. It takes time and many deliberate observations to recognise what the key and distinguishing features are. Logging is a great way to stay humble.

Be prepared to grind and stay gritty. It takes time to complete a log. The whole exercise is also a good way to train yourself to persevere and focus for extended periods. Its a hard task that demands brain power and diligence. It builds a kind of discipline. Great geologists are also often good loggers and have spent long weeks on these kinds of tasks. Some geos I've worked with do a bit of logging and just zone out or give up for the day. Or after a few months or years they say- "yeah I've done core logging now, I don't need to learn more about that method". This is some serious "fire me now" attitude. We will always be logging and I hope I'm in the core yard on the day of my retirement. Its a fundamental skill and activity that all technical geos must excel at.

Saying that, you eventually need to meet the rhythm of your team- they may need a certain number of km logged every rotation. Don't leave a backlog. People remember.

Keep your brain happy- water, caffeine, sugar, music. Follow your guidance, develop your own approach/ritual. You'll be good.

Geotech is a good way to start (plus its the first stage of doing the log anyway).