This article covers advanced concepts when designing your campaign flows.  You need to be familiar with Smart Campaigns before reading this article:

Building smart campaigns

Auto-responder Priority

If you have a campaign that sends an email following a form fillout, you should make sure that theSend Email flow step comes first.  You can put other flow steps after that.

People who complete a form expect a quick email response.  If you put the Send Email first, Marketo will assume this is an auto-responder campaign and thus needs to be prioritized higher.

If you put the Send Email step later in the flow, your campaign may be prioritized lower causing the email response to be delayed.

Add Choice

The Add Choice option in a flow step lets you execute flow steps based on a specific condition.

Say you're building a scoring campaign based on the lead's job title -- 10 points for a CEO, 8 for a VP, 6 for Director, and so on.  Instead of building a separate campaign for each title, you can use Add Choice to put this in one flow step.

Create a new campaign called "Job Title Scoring."  In the Smart List, trigger the campaing to launch when the Job Title changes:

Open the Flow tab and drag in the Change Score step.  Then click the Add Choice button.  This adds a "Choice 1" and "Default Choice" to the flow step.

In the "If:" part of the choice, you can pick which field should be checked for what value(s).  In the example below, the lead's Job Title field will be checked to see if it matches CEO.  If so, the lead will get +10 points.  Otherwise, the default choice will run -- no score change.

Click Add Choice again to add a second choice and set it up to add 8 points if the lead has "VP" in the title.  When there are multiple choices in a flow step, only the first matching choice is executed.  If no choices match, the default choice will be executed.

Add the remaining flow steps.  Below, you can see how it might look like.  If you ever want to get rid of a choice, click the red X to the right of that choice.