So I'm reading the Wiki about making my wallet secure. And it's talking about using a twelve character password and having one wallet for savings.
But my BTC client just boots right up with no password required
And when I try to install another client on my iMac it accesses the same wallet.dat file. Or I think that's what it does, as it shows my balance and transactions.
So what's up with that? Where do I go from here? Does Mac need it's own wiki?
You should always encrypt your wallet with a strong password.
If your wallet is not yet encrypted, you should set it up now.
If you are using bitcoin-qt, you could do so for clicking Settings -> Encrypt Wallet.