1. Start from a small level
2. Get enough savings before
I don't understand what you mean by small level but if I may say, now, in Bitcoin, there is no small level. Just dont wait for it, buy in any chance you get.
And again, you don't have to wait till you save up, $5 dollar Bitcoin now can worth thousands in years to come. Therefore waiting to get enough savings before buying equals to not buying at all. Or even missing out buying with a good price.
It is way better to begin your journey as a trader or investor with a small amount of money that way if you happen to make a mistake that mistake is not going to be as costly, you're not going to get as upset and finally you are going to learn something from that experience, something which is invaluable in the markets.