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.
You’ll find that different exchanges cater to different markets. Today, most countries have at least one cryptocurrency exchange specializing in their own currency. There are exchanges that can accept New Zealand Dollars in exchange for bitcoin, for example. Other exchanges are known for certain pairs. Bithumb, for example, has particularly strong liquidity in the ETH/KRW (South Korean Won) pair at the moment (and it’s easily the most popular cryptocurrency exchange in Korea).
Known for handling one of the largest Bitcoin volumes out of all the crypto exchanges globally, Bittrex allows you to decide the trading rates with a service fee of around 0.25%. Moreover, a lot of your time will be saved as the verification process in Bittrex is pretty fast which allows you to start the trading process without any major halt. The platform supports two types of accounts namely, Basic and Advanced with withdrawal funds up to 3 BTC/day to 100 BTC/day, respectively.

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.