You need Clear Red X-27 (Tamyia), it’s very useful paint when you have to do some blood. Just put some paint on plasticard or something else that you have (I used cap from spray ;), add a drop of Scorched Brown or Black to get right blood color. I use sometimes pure Clear Red color to get another effect. When the paint is thicker, take old, tired brush and apply your dirty, bloody crap.
Add some polymer glue to blood from above and wait until it is almost dry, you’ll see – ugly, strings…
Here is an example how it looks.