Update README.md

README.md

@@ -76,24 +76,51 @@ The default is to use environment variables, but you can opt-in to the local ins
 
 ### Assuming Roles
 
-Best-practice is to have a read-only account that you use on a day-to-day basis, and then use [IAM roles to assume temporary admin privileges](http://docs.aws.amazon.com/cli/latest/userguide/cli-roles.html) along with an MFA.
+[Best-practice is to create individual users](https://docs.aws.amazon.com/IAM/latest/UserGuide/best-practices.html#create-iam-users) for anyone who needs access to your AWS account, and [create Roles to delegate permissions](http://docs.aws.amazon.com/cli/latest/userguide/cli-roles.html).
 
-First you'll need to [setup an MFA token in the AWS Console](http://docs.aws.amazon.com/IAM/latest/UserGuide/GenerateMFAConfigAccount.html) and create a role with admin access.
+First you'll need to create the users and roles in IAM. Next, edit your `~/.aws/config` to add profiles with a `role_arn`. For example:
 
-Edit your `~/.aws/config` to add the `role_arn` and `mfa_serial` into a new profile:
+```ini
+[profile jonsmith]
+region = us-east-1
+
+[profile prod-readonly]
+region=us-east-1
+role_arn = arn:aws:iam::111111111111:role/ReadOnly
+source_profile = jonsmith
+
+[profile prod-admin]
+region=us-east-1
+role_arn = arn:aws:iam::111111111111:role/Administrator
+source_profile = jonsmith
+```
+
+Now when you use the `prod-admin` profile, `aws-vault` will look in the `jonsmith` profile's keychain for credentials and then use those credentials to assume the `Administrator` role.
+
+### Using MFA
+
+You should also require that users provide a one-time key generated from a multi-factor authentication (MFA) device when they attempt to make a call using the `prod-admin` profile.
+
+First you'll need to
+[setup an MFA device](http://docs.aws.amazon.com/IAM/latest/UserGuide/GenerateMFAConfigAccount.html). You can then [set up your IAM role to enforce MFA](http://docs.aws.amazon.com/cli/latest/userguide/cli-roles.html) using `"Condition": { "Bool": { "aws:multifactorAuthPresent": true } }`. Next, add a line to the role profile that specifies the ARN of the user's MFA device. For example:
 
 ```ini
-[profile prod]
+[profile jonsmith]
+region = us-east-1
+
+[profile prod-readonly]
 region=us-east-1
+role_arn = arn:aws:iam::111111111111:role/ReadOnly
+source_profile = jonsmith
 
 [profile prod-admin]
 region=us-east-1
 role_arn = arn:aws:iam::111111111111:role/Administrator
-mfa_serial = arn:aws:iam::222222222222:mfa/jonsmith
-source_profile = prod
+mfa_serial = arn:aws:iam::111111111111:mfa/jonsmith
+source_profile = jonsmith
 ```
 
-Then when you use the `prod-admin` profile, `aws-vault` will look in the `prod` profile's keychain for credentials and then use those credentials to assume the `Administrator` role. This assumed role is stored as a short duration session in your keychain so you will only have to enter MFA once per session.
+Now when you use the `prod-admin` profile `aws-vault` will prompt you for an MFA token. This assumed role's session is stored in your keychain so you will only have to enter your MFA once per session.
 
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