Time; words and actions consistently matching up; your gut
You have to trust yourself and your ability to make that decision on whether person that can be trusted.
Give it time. Eventually you'll know in your gut if you should trust them or not.<br />
If you have to question if someone should be trusted- they probably shouldn't be.
dont judge right off the hop, even if a person may lie. its doesnt mean theyre not trust worthy. if they are still apart of your path years later give them the benfit of the doubt. they may be trying to protect u, and u may find out and see it as an insult. but if theyre still there u will know. my advise it not to be too skeptical of anyone right away....u may be surpised
By their history, and whether or not they're sincere about the little things.
They like big butts so they can not lie
Stalk them, see if they do anything untrustworthy.
Only time will tell.
You never do just have to choose to believe or not