Savings generates interest, but only after you've accumulated a decent amount. Don't use that until much later.

Use the "market" option, you can sell your SBD for Steem. There's a witness, @blocktrades, who also runs an exchange for SBD straight to SP. The exchange rate isn't quite as good as going through the market and buying Steem directly, but it's quick and easy. So take your pick, really...