JOEL - Actually, we like to concentrate more on what we should do and be rather than worry about the "don'ts". The main do's for example are as Jesus said, to love God and love our neighbor. Those two take care of everything. But if I were to make a list of the dont's, here is what it would include:

Don't forget to talk to God
Don't forget to listen for His answer
Don't forget to love your neighbor
Don't forget to love your enemies
Don't forget to read your scriptures
Don't forget the Ten Commandments
Don't forget the teachings of your parents and Church leaders.
Don't forget to have some fun.
Don't forget to say thank-you
Don't forget to say I'm sorry
Don't forget to say I forgive you
Don't forget to shun Satan's influence
Don't forget to do your best
Don't forget that Jesus loves you.
Don't forget who you really are; a child of God.

Not the list you were expecting? OK I'll try again.
A list of things a Latter-day Saint should not do:

No swearing (including taking the Lord's name in vain)
No sexual sins(fornication, adultry, pornography, homosexual behavior, etc.)
No R or X rated movies, magazines, books etc.
No dating before age 16
No coffee, tobacco, black tea, illegal drugs, alcohol
No shopping, sports activities, or recreational activities on the Sabbath.
No working on the Sabbath if possible
No breaking of any of the laws of the land
All the other don'ts as recorded in the Bible