First, peel the potatoes and rinse them. Then cut the russet potatoes into Thin fry strips.
Now soak them in a bowl of cold water along with a few tablespoons of table salt for 10-15 minutes. This will allow the salt to draw out the extra starch and moisture from the potatoes for crispier fries.
Then rinse them with cold water making sure to really rub the starch off. Then pat them dry as best as you can.
Now lay the fries down on a rimmed baking sheet and drizzle with the avocado oil and season with salt and pepper. If you don’t have avocado oil, make sure to use a high smoke point oil like corn or vegetable oil. Olive oil won’t work as well here. 
Arrange the seasoned fries on the air fryer basket and cook at 400 degrees Fahrenheit for 15 minutes, making sure to toss them every 5 minutes.
Notes
How to reheat homemade friesJust put them back in the air fryer and heat for about 5 minutes, tossing halfway through. This should heat the french fries through and also make them crispy again. You can also reheat them in the oven on a baking sheet. However, I would not suggest using the microwave because it will heat them, but also make them very soggy.