Set for all items
Perhaps the most basic rule, but because of its usefulness a very common one. If a field needs to have the same value for all of your items, simply create a rule that sets these. Using 'and' statements, you can do several of these in one item.
Remove items that are out of stock
Don't want to send a certain group of items to a channel? Simply add a rule that removes these items. Common uses are for removing items that have poor margins or are out of stock.
Free shipping above price X
If the data you imported does not have any shipping price in it but the export channel does require it, you can use rules to add this information. An example would be if you provided free shipping for items that cost over €100. In this case you would actually have two rules: one for setting the regular price (see 'Set for all items') and one for items that have a price that is greater than 100. Do keep in mind that rules are applied in order from top to bottom, so make sure that you first set the regular price for all items before setting the discounted price for a subset of your items.
Add a phrase to a title
Using the 'append value' operator, you can add any word or phrase to a field such as your title. You can use this to add phrases like 'Sale' or short information about your business.
Mix and match!
Rules are extremely flexible, almost anything can be done using them. You can combine these examples any way you like.