you basically already answered your question. You need one thing and that is patience. It might sound difficult but it's really not, what you have to do is convince yourself not to sell anything you buy for the next, let's say five years. If you manage to do that  you will not only double your holdings but multiply then. For that to work of course you need a good strategy, and the best one is to find the coin that will make you the best returns. It's not very easy to do that but you can follow some rules, like investing only in projects that have experience in developing products and services, invest in ideas that make sense to you and to the future of the market, invest in projects that are undervalued and by most people ignored.