When you create a new layout in FileMaker, one of the options that appears in the New Layout Wizard is to create a "Labels" layout. You get a list of Avery numbers when you do and if the Avery number of the labels you plan on using is in the list you merely need select that option and you get a layout set up for Avery type labels.
Partially used pages of labels can be managed if you either create a blank record for each used label on the page or if you load the page with the used portion trailing and print a set of labels less than or equal to the number remaining on the page.
But if you routinely print just a few labels at a time, it is much less trouble to use a dedicated label printer such as the DYMO printer.
To handle the partially used pages, you can create a number of records equal to the total number of labels per page less one. Then you may give each record a value from 1 to the total number of records created. Now you can create run a find to select the number of "blank records" needed and the records you really need to print. Sort the records in an order where the numbered records are the first ones ( a field not used to number those records), print the found records set. Or create a script to do the same.