My honest opinion is that the easiest is to use inbuilt filtering features on a bound query. You just right click in the first field and filter on the values you want to filter down to. Now that you have all records with that values, you can repeat the process and filter on the next field for an even more granular subset of records. Nobody seems to consider such an easy method any good for some reason though.
So, another method is parameters in your source query.
then you can fiddle with code to edit the query source too, if you like to go that route - not so easy as the previous options but will work and if you have a specific need rather than a general purpose one then it may be worth it to do the extra work.