There isn’t much to say about batteries. Most are shaped or have a marking or sticker that should indicate which way they should be oriented when they go in.
I like to use a sharpie and mark my batteries with letters of the alphabet, then I take note of which ones are dead when I swap them out. A better solution is to consistently keep charged and dead batteries in unique and separate sections in your bag.
Third Party Batteries
The year is 2023 and off-brand batteries are... fine. They're fine.
Not that long ago, if you bought off-brand batteries, you carried a serious risk of damaging your equipment. Many camera manufacturers have not changed their battery design in decades (that's a good thing, actually). It also means that some of the crap old third party batteries are still out there for sale, and worse somehow.
So I still don't recommend any third-party batteries, but if the battery itself was made in the last few years, and comes from a not-complete-amazon-spam brand, it's probably fine.
An external charger is a must.
If you like to shoot in portrait mode, these grips can not only give you more battery life, but add another shutter button and some dials. You can hold your camera "like normal", and shoot portrait orientation images.
The battery slot cover flap is usually removable, which allows fancy battery-expanding camera grips – like big camera boxy extensions – to slide in. If the cover flap pops off, it may not be broken. You can also sometimes get replacement doors without replacing the entire camera.
The battery door cover can or contains an even smaller little flap on it. This is so you can insert an AC power adapter – a cable with one end into a power outlet, the other end looking like a battery, right in the camera. The cable from that needs to get through the battery door without us needing to leave it open, so it goes through the little flap.
Lithium-Ion Battery’s don’t work as well when they get very cold, so be aware if you’re taking photos while out hiking or during winter. You can try keeping an extra battery warm in your pocket and rotate them as they die (they can sometimes be magically revived by warming back up), but you’ll also probably just need more batteries.
I can't stress enough the significance of an extra battery and an external battery charger.
Shoot your camera until it is dead, then swap. Charge the dead one but you can keep shooting. Never play the 5% juiced “is this shot worth it?” game. Just keep shooting as normal, and swap when you need to.