It depends on blood clot, if you get a cut, and blood stops coming= good clot. If your talking about heart, vein, etc, you might want to go to the doctor, to see if theres a type of medicine you can take. But without going to the doctor, I'd say eat extremely heathy, and try to not eat sweets.
Keep that part of your body elevated and above your heart. If it is in your arm, put a bunch of pillows underneath it. If it's in your leg, then do the same. But I don't know about what to do if it is in any other parts of the body.