Regarding your private keys, can either keep them on a software wallet, or on a hardware wallet. The software wallet is the easiest way for beginners, but it implies that you have a computer that is properly secured (strong password, antivirus etc.) and that you do backups of your data. Remember, if you lose your private keys, the money is gone forever. As you get into cryptocurrencies more seriously, you will inevitably look for a hardware wallet, which is a dedicated device resistant to hacking where you can store your private keys (or to say it in an easy way, your crypto assets/invested money). I have already written an article on a hardware wallet, the TREZOR (see here). The most common wallets are the TREZOR and the Ledger Nano S. The TREZOR has a new model being sold from January 2018 (Model T) which will support much more currencies than the current TREZOR. The Ledger Nano S has more integrations currently, but I would recommend to wait for the TREZOR T to judge properly. Those devices usually cost around 100 USD, so once you have more than 100 USD to protect it starts making sense to get one.
As written in section Investing 3, you should never keep any valuable assets on an exchange, unless you engage in day trading. You should get an appropriate wallet to store your cryptocurrency safely. To explain the concept better, what you are storing is not the cryptocurrency itself, but your private keys, the keys that allow you to spend the cryptocurrency that is assigned to you and stored on the blockchain of the given cryptocurrency (of course each project has its own blockchain, just like each bank has its own internal banking system – to simplify heavily). Anyone who has access to your private key is in control of your cryptocurrency assets, so you must secure them. Most if not all of the wallets around have a feature called a backup phrase. It is a mnemonic sequence of words that must be written on paper and stored securely. If you lose access to your wallet, get it lost or stolen or whatever, this backup phrase should allow you to recover instantly access to your private keys and funds, after which you should immediately transfer them to a new address.
Crypto-only exchanges do not handle any fiat currency, they don’t work at all with « real world money ». They will however allow you to trade a very large amount of cryptocurrencies. They have « markets », where you can exchange mainstream cryptocurrencies like Bitcoin (BTC), Ethereum (ETH) or Litecoin (LTC) for other less known cryptocurrencies. They will offer similar services as advanced exchanges but you will not be able to cash out. You would have to convert the cryptocurrencies you own to a more common one (BTC, ETH or LTC for example), send it to one of the fiat to cryptocurrency exchanges, and then transfer it to your account. Alternatively, you could also just decide to pay for goods and services in cryptocurrency. Or you could also withdraw the money via Bitcoin ATMs (where you send Bitcoin to an address and get cash, just like you would on a regular ATM).
Why I’m buying: Spell out what you find attractive about the company and the opportunity you see for the future. What are your expectations? What metrics matter most and what milestones will you use to judge the company’s progress? Catalog the potential pitfalls and mark which ones would be game-changers and which would be signs of a temporary setback.