What should i do on call of duty modern warfare 2?

i really want to get my killstreaks high like ac130s but i cant do it i get to like predator missile sometimes to harrier but then i die i used to get loads a couple months ago i even got a tactical nuke ounce but then i had a break and now i seen to get really good kill death but no kill streaks and my friend get loads of nukes what should i do?