Cramming tissue paper up your nose is probably not the best way to deal with a nosebleed.
Here's the proper advice;
http://www.nhs.uk/conditions/Nosebleed/Pages/Introduction.aspxYou can usually stop a nosebleed yourself by pinching your nose just above your nostrils for 10 minutes. Leaning forward and breathing through your mouth will drain blood down your nose instead of down the back of your throat.
Just don't lean your head backwards (this used to be common advice for some reason), as it means the blood can drain back down your throat, and you could choke.
And obviously, lean over a sink as soon as you can, so you don't get blood everywhere.
I used to get spontaneous nose bleeds when I was a kid. You just have thin skin around the blood vessels in your nose, dry weather pretty much guarantees bleeds. Sounds like you don't get them often though if you can't tell the difference between mucus and blood.
My older brother used to get them a lot when he was younger.
He had a small blood clot on account of them in his nose, but it could become dislodged really easily, from even the tiniest of bumps/shakes of his head, so he would get nose bleeds frequently.
But yeah, in addition to that, they're just caused by a dry nose (either infection, low humidity, or just a hot environment can cause this) or by damage to the nose, like excessive picking/blowing/rubbing.
