Berkano works well on it's own, it's best to start a Bjarkan protection working on monday during the hour of the moon if possible, vibrating it twice a day with any multiple of 18 (88 is a good number aswell).
Runes don't work very well if vibrated for less than 20 reps, so try to do more than that and for the best effect vibrate Bjarkan both in the morning and evening, so twice a day.
Unless you are doing a specific working where you combine a number of runes together, you should stick to vibrating a rune with any multiple of it's Runic number, so for Bjarkan that woud be any multiple of 18 and for Ansuz (just an example) that would be any multiple of 4 as it's Runic number is 4, etc.