Take your time with the install process. It’s possible that you may breeze through it. It’s also possible that you may discover that, say, there’s something wrong with the EFI implementation of the system you’re installing to that you need to do some research to resolve. I’ve had both experiences.

Once installed, Gentoo is pretty much rock-solid, and almost any issue you have can be fixed if you’re willing to put the effort in. Portage is a remarkably capable piece of software and it’s worth learning about its more esoteric abilities, like automatic user patch application.

Do take the time to set up a binary package host. This will allow you to install precompiled versions of packages where you’ve kept the default USE flags. Do everything you possibly can to avoid changing the flags on webkit-gtk, because it is quite possibly the worst monster compile in the tree at the moment and will take hours even on a capable eight-core processor. (Seriously, it takes an order of magnitude more time than compiling the kernel does.)

Install the gentoolkit package—equery is a very useful command. If you find config file management with etc-update difficult to deal with, install and configure cfg-update—it’s more friendly.

If you’re not gung-ho about Free Software, setting ACCEPT_LICENSE="* -@EULA" (which used to be the default up until a few years ago) in make.conf may make your life easier. Currently, the default is to accept only explicitly certified Free Software licenses (@FREE); the version I’ve given accepts everything except corporate EULAs. It’s really a matter of taste and convenience.

Lastly, it’s often worthwhile to run major system upgrades overnight (make sure you --pretend first to sort out any potential issues). If you do want to run updates while you’re at the computer, reduce the value of -j and other relevant compiler and linker options to leave a core free—it’ll slow down the compile a bit, but it’ll also vastly improve your experience in using the computer.

(I’ve been a happy Gentoo user for ~20 years.)