Any person who says that the law is necessary unto salvation speaks anathema. Tithing is not necessary to go to heaven. Firstfruits is not necessary to go to heaven. Wearing or not wearing of earings is not necessary for salvation. Trying to obey all the laws in the old testament is not necessary to go to heaven (loving one another and loving God is enough, and is the only thing Christ told us to do.) Do not live your life in order to obey the ols law, because then, you will be judged by the old law, and since you obviously not obeying all the law (no one could, and that is why God sent Jesus Christ.), you will be under the curse of the law (which is inflicted upon everyone who can't obey the whole law. See Deut 28 from verse 14 for details). That is written in Gal 3:10.

Man is justified not by the works of the law, but by faith in Christ Jesus.

Gal 2:16  knowing that a man is not justified by the works of the law but by faith in Jesus Christ, even we have believed in Christ Jesus, that we might be justified by faith in Christ and not by the works of the law; for by the works of the law no flesh shall be justified. 

  Gal 2:21  I do not set aside the grace of God; for if righteousness comes through the law, then Christ died in vain.”(NKJV)

Some may say- isnt faith without works dead? Which works, I ask? is it the works of the old law, or the works of the new law given by Christ, to love one another as we have been loved? 

Gal 5:13  For you, brethren, have been called to liberty; only do not use liberty as an opportunity for the flesh, but through love serve one another. 

Gal 5:14  For all the law is fulfilled in one word, even in this: “You shall love your neighbor as yourself.” (NKJV)

Gal 4 explains that only those who believe by faith will inherit God's promise, and the son of the bondwoman (thosse who live by the law, and say that obeying it is necessary unto salvation) is to be cast out. this is because the gift of God is given freely in Christ Jesus, through belief and belief only, which is then voiced out by your confession.

Study the Word of God for yourself, and test all the words you hear (including this). This is important because Paul warns us that those who preach another gospel other than the one initialy given are accursed (Gal 1:8&9) so be careful, and preach not to please men, but God. Anything you need will be provided by God as you do his work. (Matt6:33)

Finally,, I close with this verse from Acts 21:25.

      Act 21:25  But concerning the Gentiles who believe, we have written and decided that they should observe no such thing, except [d] that they should keep themselves from things offered to idols, from blood, from things strangled, and from sexual immorality.”(NKJV)

May God give you wisdom even as you understand his Word in Jesus name.