Holding them or trading them with altcoins on trading sites like ecoin.eu. I trade my btc for LTC and wait for it to rise up but its quite bad for LTC nowadays.
Two years ago, I got some hefty profits by converting my BTC to LTC, but I'll not recommend it to anyone. In January 2013, the exchange rate was going at 1
BTC = 400 LTC. I converted one of my coins to LTC. Then a few months later, the exchange rate climbed to 1
BTC = 40 LTC. I got almost 10x profit, but lost most of it later in an investment scam.