[header] How to prevent nose bleeds [title] Don't pick your nose. [step] By far the most common type of nosebleeds are anterior nosebleeds, when the bleeding comes from the lower septum, the wall between the two channels of your nose. This area has a lot of sensitive blood vessels that can bleed profusely when irritated. 
Picking your nose is one of the prime irritations that can cause these kinds of nosebleeds. [substeps] You should generally avoid picking your nose if you want to lower your chance of nosebleeds.