The capital in trading depends on how much profits you want to get, and for that you don't really need any minimum amount to start, you should just keep in mind that you can invest any amount according to your needs of profits but there is no any recommended minimum amount to start trading with.
But if a newbie wants to start trading and he doesn't have enough budget for starting with it. I guess, 0.005-.01 BTC is going to be enough for buying some good alt coins that can give you profit in the long run. And it is also a good dry-run so whenever you fail with your first start then that is just fine for it is affordable to lose.
Exactly, because the more experience you are going to get as you trade then you are going to be more confident in the long run as a trader. But there are some new entrants in trading that are confident immediately thinking that they are going to get profit as they invest and start big amount with it, but always remember ladders are not starting at the top, but in the low.