When i was new to the cryptoworld i also have the same queation. How do i start? Well, what i did was buy bitcoin and trade the with the altcoins. If you want to know which altcoin would guarantee growth in your investment, the answer would be none. Growth depends on how you hndle your coins. Some people mine, some people gamble, some people do day trade, some people ghold their coins. If you wnt to be safe, just stay with the coins that has already built their names: bitcoin, ethereum, litecoin, etc. Good luck!!