Learn the lingo. BTC is the symbol for Bitcoin. Bitcoin is a type of cryptocurrency. An altcoin is a coin that isn’t Bitcoin (like Ether). Limits, stops, exchanges, shorting, forks, ICOs, margin trading, etc (search for any of those on our site). It is way easier to invest and trade if you understand the common terms used. It is also easier to make friends in crypto groups if you know investing lingo and basic memes like “hodl.”
Coinbase/GDAX will want more personal information than you’ll feel comfortable giving them; there is no way around this. The more information you give them, ID, Bank account, credit card, etc., the higher your limit and the less restricted your account will be. Don’t let this scare you off from becoming a cryptocurrency investor. Every other exchange user went through this process; you have to also. Since you have to trust someone, Coinbase/GDAX is a good bet.
Always pay attention to Bitcoin. Most altcoins (every cryptocurrency except Bitcoin) are pegged more closely to Bitcoin than Asian currencies were to the USD during the Asian Financial Crisis. If Bitcoin price pump drastically, altcoins price can go down as people try to exit altcoins to ride the BTC profits; inversely, if Bitcoin prices dump drastically, altcoin prices can go down, too, as people exit altcoins to exchange back into fiat. The best times for altcoin growth appear when Bitcoin shows organic growth or decline, or remains stagnant in price.