Mites are pretty inevitable. You will get at least some type of mites in your culture. Thankfully there are different types of mites. White mites are called grain mites. They will not really impact your culture too bad. You can microwave your media that you've prepared for about 30 seconds or so when making it. That will usually destroy any mites that may already be in the media. Then you would let it cool before adding your flies.

As for black mites.. they are a little tougher. You can tap your flies into a cup with a bit of calcium powder before adding them to the new culture. This has been shown to lower the amount of mites transferred to the new culture. If either type of mites become prominant your culture will crash.. or have a very short life cycle.

It's great that you are researching ahead of time!

-Edit- One of the most important things.. which I failed to mention.. DO NOT keep your new cultures close to your old cultures. Mites will transfer from your older cultures without an issue. That is why it is important to keep them on a mite paper/paper towels sprayed with mite spray, and to make sure that your lids do not touch each other.