Onboarding Welcome Sequence

Trigger: Matches segment
Audience: Subscribed users, future additions only (you only want people who subscribe going forward, you don't want existing users to receive this)
Exit: Move through entire Journey
Reentry: No (you only want users to receive onboarding once)
Content: Welcome new users to your app or website, encourage them to accomplish certain tasks over the first several days or weeks

Re-engagement Campaign

Trigger: Inactive for 1 week
Audience: Subscribed users (you may want to exclude certain segments like paid customers if your goal is to get more free users coming back)
Exit: Move through entire Journey OR becomes active
Reentry: Yes, every 7 days (you're fine for reengagement to happen every time they haven't opened your app in a while)
Content: Remind users to come back to your app when they haven't opened it in a while, entice them with rewards or discounts

Abandoned Cart

Trigger: Matches segment
Audience: Segment with a tag “cart_item”, and ensure to tag your users when they have items in their cart
Exit: Moves through entire journey OR segment with “cart_item” empty (when a user completes their purchase then remove this tag)
Reentry: Yes, every day (you're fine sending a user this campaign once daily, every time they abandon their cart)
Content: Remind users to come back and purchase the item they didn't complete checkout with. You might want to have different branches for different item categories or personas e.g. if they have purchased previously or not

Promotional Campaign

Trigger: Matches segment
Audience: Subscribed users or target the segment your promotional campaign is relevant to
Exit: Moves through entire journey OR enters a particular segment which is the goal you want them to complete e.g. purchase
Reentry: No (if this is a one-off campaign then send it once)
Content: Prepare them for the event, remind them when it starts, offer a discount or reward as it gets close to ending