I have witnessed to Mormons and it can be a bit intimidating because they use “our words with different meanings”.  It is always good to let them explain the terms they use, etc.   First, I would use the law and the commandments to allow the holy spirit to convict of sin.  the following is a “method” but I prefer it to roman’s road because it is more specific vs. “all have sinned” (ever told a lie? hated someone? lusted? etc).  get them to admit to being an adulterer, murderer, etc.  guilty or innocent?  heaven or hell?  does that concern you?  does that concern you enough to do something about it?  do you know what God did so you don’t have to go to hell?  do you know what God tells you to do? (faith and repentance).  after taking them through this approach (which I like because it steers away from using heaven, blessings, etc as drawcards) this is where they will either see the difference or you can then answer objections etc.

if there are objections I would get into asking them what they are trusting in…..ie hold out the book of Mormon and the bible and ask them what they would trust for absolute truth.  then you can show them the difference between the real and counterfeit.  examples, show them science facts in the bible and science errors in the book of Mormons.  the key is this is not an intellectual thing.  it is very tempting to turn this into a debate and just want to win.  we can win and they still end up in hell.