2. Dollar cost averaging, don't jump in at the market rate, unless you're just making lots of small bets. You can place orders that get filled when the price drops below a certain point... you effectively have money waiting to buy a dip in that case. You can also do the reverse, sell at a certain point. Learn all the different transaction types.
3. Start small... do some small trades to see how things work, and make sure everything is as expected.
4. There is a very strong element of Ponzi scheme in the crypto space... if you can, watch the inflows and outflows in the meta.
5. Never panic sell, or buy because of fear of missing out. Play it for the long term. In the stock market, emotions lose money, the same is true in crypto.
Step 1: get general investment knowledge first. You need to know your alternatives.
Step 2: invest in Bitcoin or Ethereum by using appropriate bankroll management. Also see mikewarot his comment on the dollar cost averaging strategy as one way of appropriate bankroll management. For conservative investors I recommend 1%. For super hyper aggressive investors that want to yolo in all their money (including the money of their parents and grandparents) and expect to be rich by Sunday, I recommend 10%, NO MORE (feel free to ignore the shouting if you don't fall into this category, if you do, then reread my recommendation including the shouting 10 more times).
Step 3: come back in 5 years
As for exchanges, I'm most happy with Coinbase. I've used: Kraken, Binance, Poloniex, Crypto.com, Bitfinex, Bittrex and a few I don't remember. Most of them I don't trust. I'm still in doubt about Binance and Crypto.com. Binance: because it's unregulated. Crypto.com: because they either have unexpected charges that they don't tell you about or they have very inefficient spreads.
Todo step 1:
A. Read the Intelligent Investor. Understand it. Most of the value investment material is relevant during market crashes, and a lot of timeless knowledge is in there. Learn about the difference between trading and investing, margin of safety, etc.
B. YouTube channels to watch: The Plain Bagel, Patrick Boyle.
C. Understand: CAPE and Shiller's work in general, ETF investing (check Bogleheads.org) and Fama's efficient market hypothesis. Shout out also to the Kelly Criterion.
D. Whatever you do, do not learn anything about trading. And if you do, do not learn anything about technical analysis and assume you need at least a master degree in statistics and probability theory.
You need to know if other assets are actually a better investment for you. I'm currently learning about real estate and options as both have financial leverage factors in them. Though, I don't think you need to know about them as an alternative as they require you "getting into the investment and/or trading rabbit hole". The above stuff, while it takes about 50 hours, that's it.
If you do, consider whatever money you put in to be lost and plan accordingly.
Best time to buy is when you don't hear about it on the news or when bad news happens.
Worse time to buy is when the news tells you bitcoin broke a record.