Unfortunately your question is too vague to provide you with any helpful information. It is impossible to tell you what would help your case without knowing any of the facts.
I can tell you that it doesn't necessarily matter if the firearm or drug paraphernalia is actually yours; what matters is whether you were in possession of those items. The classic example is someone who, when caught with a bag of marijuana, says it's not theirs but they're holding it for a friend. The charge is possession, not ownership.
Grand Theft of a Firearm is obviously a little different than a simple possession charge, but often times people are charged with theft if they are in possession of recently stolen property.
Again, without knowing the facts it is impossible to give you any information.
