if you want growth your bitcoin much alternative you can use
the first you can trading , trading with to option
1 trading bitcoin pair altcoin you can use poloniex bitrex or c-cex
2 trading bitcoin pair fiat money you can use btc-e bitstamp coinbase huobi okcoin
and then you can lending your bitcoin
lending bitcoin you can use poloniex or bitfinex
i use this way too to grow my bitcoin. i am trading btc-altcoin in poloniex and also i am lending my bitcoin on poloniex so in both ways i can grow my amount of bitcoin. i don't really matter about the rate of lending, for me its like free lunch i've got from lending bitcoin to traders. maybe for OP its only small amount but for me its still satoshi and can make my satoshi grow.
I also do trading altcoin to grow. This is the best way I think. because trade altcoin clearer and favorable for me. but sometimes I also invest in projects altcoin(ICO), because everything associated with altcoin always beneficial for me