EDIT: #10 Bonus (Suggested by @kerstenwirth ) — always check the ticker symbol. Ticker symbols are not universal, and may vary from exchange to exchange in rare cases. Those cases, though, can come back to bite you. For example, Bitcoin Cash trades on some exchanges as BCH, while it trades on others as BCC. BCC is also the ticker symbol for BitConnect, which was recently outted as a Ponzi Scheme. If you bought BCC under the impression was Bitcoin Cash, you would’ve lost a lot of money.

The crypto market is a ‘giving’ mechanism, not a taking mechanismAugust 9, 2015How simple it is for amateur traders to hit the buy button, without even the slightest hint of an insight into the hidden forces that impose their will on the movement of price throughout each and every segment of this market. How simple it is to adopt such basic view of the digital currency markets

There are many groups on Facebook where you can find likeminded folks who will happily talk crypto all day but the problem is that 99% of these groups are filled with people who have only a very basic understanding of cryptocurrency and the knowledge available here is not particularly strong. I have recently left almost every single group on Facebook as, in my opinion, they are largely filled with FUD.
Dollar cost averaging one’s purchases of Bitcoin reduces risk in sudden changes. This reduces the sting of or sudden pricing changes, reducing reliance on a single point of entry. By increasing your Bitcoin investment over time, you reduce the desire to buy or sell often. If there’s anything we’ve learned from the long run is that Bitcoin is here to stay (knock on wood). Stick to your gut, but don’t ignore others.

Disclaimer: This information should not be interpreted as an endorsement of cryptocurrency or any specific provider, service or offering. It is not a recommendation to trade. Cryptocurrencies are speculative, complex and involve significant risks – they are highly volatile and sensitive to secondary activity. Performance is unpredictable and past performance is no guarantee of future performance. Consider your own circumstances, and obtain your own advice, before relying on this information. You should also verify the nature of any product or service (including its legal status and relevant regulatory requirements) and consult the relevant Regulators' websites before making any decision. Finder, or the author, may have holdings in the cryptocurrencies discussed.
There is also an Ethereum-based ETF pending regulatory review, and many such products are likely to follow. For now, there are just a few options available. For example, ticker symbol GBTC is one such security listed on the US-based OTC Markets Exchange, and is available at major online brokerages such as Fidelity, providing stock market investors a way to gain exposure to Bitcoin without buying the underlying or using a derivative.
You don’t have to buy a whole coin. You can buy fractions of coins. Bitcoins are expensive currently in 2018, so consider buying fractions of a coin to start if you don’t have a big bankroll. It has historically been a mistake to buy only ETH and LTC because BTC costs more. You should consider which one is most likely to increase in and retain value. Buying all three in equal dollar amounts, and ignoring how many of each coin that amounts to, is one way to avoid making the wrong choice based on price tag per coin.
Don’t be greedy. No one ever lost money taking a profit. As a coin begins to grow, the greed inside us grows along with it. If a coin increases by 30%, why not consider taking profit? Even if goals are set to 40% or 50%, you should at least pull out some of the profit on the way up in case a coin doesn’t reach the goal. If you wait too long or try to get out at a higher point, you risk losing profit you already earned or even turning that profit into a loss. Get into the habit of taking profits and scouting for re-entry if you want to continue reaping potential profits.