The best way to increase your bitcoins is by investing them in different altcoins and with that you will be making regular profits at regular time and it will also help you in multiplying your bitcoins which will eventually increase the level of your coins in your wallet.
This, but to add to this statement I will suggest going for ICO's that's how you get the best price for altcoins.
Yes investing in ico can bring huge profits for you but you need to make sure that you are investing in right projects as many icos have turned out to be scam in the past where only the devs have made money out of it living their investors penniless.
yeah i also invest in ICO many times and i get a big profit and there a lot of people investing their money in ICO because we can make a good money through ICO of any trusted coin and first of all get information that which type of currency are strong and secure then invest.