Step 1: Go to Bancor.network
Step 2: Create a wallet. They have options to use the Trezor and Metamask as well for added security.
Step 3: Use their fiat gateway to purchase ETH with your credit card.
Step 4: Click Buy on the ERC20 token(s) you'd like then follow the prompts.
And done!
Using other exchanges, you would have to add an extra step of moving the ETH to an exchange, and if you wanted to secure that purchase you would have to move it out again. You can trade directly from your Trezor or MetaMask wallet with Bancor. How amazing is that!