You will be buying BTC anyway to enter the crypto market. The question becomes do you hold on your BTC or traded for ALT coin?
BTC is an amazing store of value, its history speaks for itself. ALT coin varies greatly, some are well established, and some are not, and riskier to invest in, but also reward could be worth it.  It all depends on what you are looking for. I am trying to balance 30% BTC, 30% ETH and 40% ALT coins.

However, it's not so easy to keep it this way, cause I tent to trade my BTC and invest in an awesome ALT coin project. 

Investing and Trading is fun stuff but it like anything else it takes time to build an impressive portfolio  Good luck and Happy Trading!