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.

Define and write down the conditions under which you'll enter a position. "Buy during uptrend" isn't specific enough. Something like this is much more specific and also testable: "Buy when price breaks above the upper trendline of a triangle pattern, where the triangle was preceded by an uptrend (at least one higher swing high and higher swing low before the triangle formed) on the two-minute chart in the first two hours of the trading day."
Assess how much capital you're willing to risk on each trade. Many successful day traders risk less than 1% to 2% of their account per trade. If you have a $40,000 trading account and are willing to risk 0.5% of your capital on each trade, your maximum loss per trade is $200 (0.005 x $40,000). Set aside a surplus amount of funds you can trade with and you're prepared to lose. Remember, it may or may not happen.

A word on exchange balances: it is NOT RECOMMENDED to keep your cryptocurrency assets on exchanges. There are countless documented cases of people who lost access to their funds, either because their account was disabled, or because legislation forbade the exchange operator to give access to users based on their geographical location. Some exchanges have been hacked in the past and will be hacked. It is RECOMMENDED that you use your own wallets, that you secure them properly (more below) and that you limit the cryptocurrency held in exchanges only to carry the business/transactions you have to, and for the most limited amount of time, to reduce exposure.
For example, there may be three buyers who have placed orders for buying Microsoft shares at $100, $105 and $110, and there may be four sellers who are willing to sell Microsoft shares at $110, $112, $115 and $120. The exchange (through their computer operated automated trading systems) needs to ensure that the best buy and best sell are matched, which in this case is at $110 for the given quantity of trade.

There are two types of brokers: full-service and discount. Full-service brokers tailor recommendations and charge higher fees, service charges, and commissions. Most investors are willing to pay these higher fees because of the research and resources these companies provide. With a discount broker, the majority of research falls on the investor; they just provide a platform to perform trades and customer support when needed. Newer investors can benefit from the resources provided by full-service brokers, while frequent traders and experienced investors who perform their own research may lean towards platforms with no commission fee.

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.
Rarely is short-term noise (blaring headlines, temporary price fluctuations) relevant to how a well-chosen company performs over the long term. It’s how investors react to the noise that really matters. Here’s where that rational voice from calmer times — your investing journal — can serve as a guide to sticking it out during the inevitable ups and downs that come with investing in stocks.