Either on your Campaign feed on the home screen, or on the Campaign details screen, you can favourite campaigns by tapping the orange Buengo heart on top of the main image.

You can also favourite a Campaign on an Item's detail screen, tapping on the grey Buengo heart next to it.

This will allow you to save the Campaign on your profile, under "Campaigns" and "Favourites" tab, and also follow news and updates on the project.