How easy is it to get a bloodclot? How can you prevent and avoid? Also can standing and sitting cause them?

Blood clots rapidly. when not flowing adjacent to endothelial lining which constantly suppresses both platelets & the 12 clotting proteins (at multiple steps) which operate as a chain reaction while also stimulating the chain of blood clot destroying proteins. When endothelial lining not present (such with the break of a blood vesse) or damaged (within a blood filled space) the seasaw relationship flips & blood clots.