If the fries aren't completely dry before cooking, they will be too moist to crisp, and the soaking of the fries will have been a waste. Use a towel, let them sit out for a bit, or dry them with a fan to make sure they're totally dry before oiling them up.
Add only 1 tablespoon of oil is needed or the fries will be too soggy to get crispy. Even worse, they might taste like oil - ick! In a large bowl or plastic re-sealable bag, pour in 1 tablespoon of oil and mix thoroughly. This is the bowl that you'll also season your fries in.