Regarding to investment, it is always personal favorite, choice and decision so it is very tricky to ask for which coin is the best.
If you ask me, I would suggest bitcoin is the best. It is true for all crypto investors but it does make more sense for newbie crypto investors because they are highly lack of knowledge and experience to choose good altcoins (altcoins mean alternative cryptocurrency, that excludes bitcoin). Most of altcoins are shit ones, and even they are good altcoins, their price will do highly volatile and decrease too much in bear market period.
Regarding to bitcoin, you can buy it on exchanges, ATMs but the key point is you have to learn how to store your bitcoin yourself and be responsible for your bitcoin. It will in turn include your bitcoin private key. Whoever have access to you bitcoin private key, they will have access to your bitcoin and they will steal your bitcoin instantly.
Note that if you use bitcoin wallets to store your bitcoin, you should set up strong password for your wallets, but remember that password is to protect your bitcoin private key. So if someone have access to your bitcoin private key, they don't need to have your wallet password to steal your bitcoin.
[GUIDE] How to Create a Strong/Secure PasswordBesides
Keepass, you have another option to use
BitwardenVerifying wallet after downloading, before installing and using is important. You can do this or not, it's your choice but I recommend you to do this.
Electrum wallet - Update safely and avoid phishing wallets?⚠⚠️⚠~Beware on active phishing Electrum websites~⚠⚠️⚠ (Collection list updated)To start with bitcoin, this one is the first priority for you:
https://bitcoin.orgThen, read lots of threads listed there, from basic to advanced, in the section for bitcoin.
[GUIDES] on Bitcointalk. Index thread (until there is a dedicated subforum?)Newbies - Read before using exchanges or investingRead those threads and documents on bitcoin.org to know how to back up your wallets, then retest your backup before using that wallet.
There are list of bitcoin exchanges:
https://bitcoin.org/en/exchangesThere are exchanges that ask for KYCs, and there are ones that don't ask for KYCs, so you have to choose ones that fitted to your needs.
You can check more there too:
https://localbitcoins.com/To safely move your bitcoin, please read:
How to lose your Bitcoins with CTRL-C CTRL-V. You can apply this guide to move altcoins, it is useful not only for bitcoin.
Lastly but very important, you should think of secondary plan that will be helpful for your husband/ wife/ children/ relatives to retrieve your bitcoin in worst case when something really bad suddenly happens to you.
It is an advanced tip but very important for all bitcoin investors.
Using Locktime for inheritance planning, backups or gifts