One interesting problem you will have after you have acquired some coins is how to store them safely. And if not for the actual coins then how to store the passphrases and seeds you might have for your coins or wallets. Or really anything of value that you want to secure.
You have some general options:
1 - Leaving your valuables at home (not recommended in case of a fire or break in)
2 - Locking them into a bank vault (I don't like it because you are not in 100% control, and in the case of a robbery don't count on getting any sort of compensation for the lost cryptoccurrency)
3- Putting them in a safe at home. (In this case you have more control, but in my view it is like putting a big crosshair on yourself in a warzone. If someone would break in, they know exactly what to target.)
None of these options are as cheap and as secure as storing your valuables underground. This way you are basically bulletproof against theft, fire, most natural disaster and electric outage.
Now there are some circumstances that help with storing your valuables underground, the foremost having some property to store them on. If you live in a city it might be difficult to find a spot. But if you live in the countryside or have your house with a plot of land or garden this is a very smooth process. You could also just dig down your treasure in the woods, but in that case make double sure you know exactly where you dug it down. Also you might have a grandmother that owns a house with a plot of land so you could dig there, just make sure not to dig up her rose bushes!
As for what to store your valuables in when you dig them down, not much beats a surplus ammo can. These babies are not only waterproof (and most likely explosive proof). They also shield against EMP blasts as long as the content that you want to shield from the blast does not touch the metal body of the case. And you can get them dirt cheap.
Next if you are going to store papers, like your SEED phrase to your Trezor wallet or your paper wallets etc I would also buy a laminating machine. These are also very cheap and will encase your papers in protective plastic, making them having another layer of security against water when you put them in your ammunition case. It is always good to be double, triple secure.
As for the practical stuff on the actual digging you should of course make sure no one is actually looking when you dig! And never tell anyone about your secret stash, not even the people you trust. That person might tell someone he/she trust, and so on. Let's be honest, digging down and securing your valuables will make you look like that tinfoil hat paranoiac person in most peoples eyes (people who prefer to keep their valuables in the "safe hands" of the state) A perfect topic for gossip.
Also don't mark your spot with a big red X or something on the ground or put in a GPS coordinate of the dig in your phone. Instead put something on the spot that is mundane to people, but something you remember and is striking to you, and then take a general picture of the area where your mark is seen. After you have taken the picture you can remove the marking from the area. This way when you look at the picture of the area you took you will know the mark you have left in the picture is the mark of the dig site, but other people will not notice it as anything special if they look at the picture.
It is a good habit to check your stash every 12 months or so to make sure everything looks good and clean.
Happy digging! :)