Deuterocanonical Law is divided into three segments, and it has been understood this way since long before Christ was born. Those three segments are: Ceremonial Law, religious precepts that must be followed for religious Jews to participate in Judaic ceremonies; Civil Law, legal statutes concerning interpersonal conflicts to be enforced by a Jewish government; Moral Law, rules by which all people should live, regardless of religion or government. Ceremonial law only applies to religious Jews. If you are a non-Jewish Christian, these don't really apply to you. The civil law should technically be applied in Israel, but that's none of my business. This leaves the moral law. So, how do we tell what's what based on these statutes?
Paul gives us some hints in Romans. The law is there to reveal the truth about sin, but we are no longer bound by the law. Should we then sin? Certainly not! No longer being bound by the law is a higher standard than being bound by the law. We are to instead read the law looking for the meaning behind the law and thus discern what we should do based on the character of God, thus the commandments 'Love the Lord your God' and 'Love your neighbor as yourself' being given as a summary of all the law and the prophets.
So why don't we freak out about kosher laws and such? Most of these had to do with an allegory of mixing. Hebrews were instructed not to mix with the surrounding nations. As a constant reminder, they could not mix fabrics. Death could not be mixed with life. Only the purer, cleaner animals could be eaten. Hebrews had to rest, and so did their fields. Some of them had beneficial secondary effects, but they are all reminders of who the Hebrews were supposed to be. Christians do mix and do not separate themselves, so laws intended for such things don't apply to Christians.
There are also clues in the language as to whether God says this is never ok or if it's just a disqualifier for entering the temple for a few days.