Right now, cryptocurrencies are pretty much the new wild west of investment vehicles. If you are willing to bet governments are going to throw out their fiat currencies and legitimize cryptos, well then the least I can do is send you to a place that reduces the fees on buying and selling this crazy investment vehicle.
The average investor (or speculator) is likely using something like Coinbase, the quick consumer platform, to purchase cryptocurrencies like bitcoin, etherium, litecoin, and bitcoin cash. There is an app and you can buy cryptos on your phone! However, the fees are relatively hefty at 1.49%. I was on the subway recently and saw an older gentleman on his Coinbase app with over $250,000 in cryptocurrencies. If he sold that day, he would have spent $3,725 in selling fees alone.
Instead, I suggest using Coinbase's institutional trading platform called GDAX, which charges fees of .25% to .30% (fees are based on the amount you are trading). Saving 1.24% is pretty significant over time, especially if you are more of an active trader. I will say it's a little bit less user-friendly, but if you just google "GDAX how-to" videos, you should be up and running in 10-30 minutes depending on your experience. If you want to get fancy, GDAX allows you to add in stop-losses (Think: If the price of bitcoin drops 10%, it automatically sells for you), to prevent you from losing everything. And yes, you can absolutely lose everything. The best part is that if you already have a Coinbase account, you automatically have a GDAX account, because they are owned by the same company.
Pros: Saves you money on fees, allows you to automate trading so you don't have to look at your trades 24/7, and already tied to Coinbase account
Cons: There is a bit of a learning curve, but nothing too hard.
Side Note: My suggestion on investing in cryptocurrencies is simple - put in expecting you will lose it all. It's honestly like going to Vegas. Invest, wait a year or longer (so you aren't taxed on short-term investments by the IRS), and then sell.