On cryptocurrency mining: As noted, one way to invest in cryptocurrency is via cryptocurrency mining. That is a valid way to start investing if say you love computer gaming and need a new rig and want to invest in small amounts of cryptocurrency while maybe making back some of the cost of the rig (and maybe even breaking even) but that is an entirely different subject. The average investor will want to trade USD for cryptocurrency on an exchange and avoid the complexities and investments of mining. In all cases, unless you already have a good rig with a great graphics card, you’ll need to put down USD upfront anyway.
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.