The ideal initial amount is 0 (zero), you earn some coins in airdrops, giveaways or doing some simple tasks online and then you build your portfolio from there.
That's how you really learn to navigate in bitcoinland.
If you have enough money to invest, money your can afford to lose, then just buy bitcoin every month, sit on it, and in a few years you'll have a nice sum of money.
I agree. There are some decent airdrops and bounties, such as signature campaigns, available, so not having money is not an excuse to avoid bitcoin. If people spent as much time doing these tasks as they do arguing with others or wasting time online, they would eventually own plenty of cryptocurrency.