“A religious discussion creates both Direct Light and Reflected Light.
When you speak to a friend about G-dliness,
the information he [she] receives from you is Direct Light.
What you gain from him [her] is Reflected Light.” 
How can any of us with less than complete, perfect emunah encourage others? Rebbe Nachman explains it here.
Our own emunah, however shaky, can be strengthened by the positive statements we make to others about G-d and bitachon, trusting. In Rebbe Nachman’s words, it’s like a light that we shine on a friend’s face on a dark night. The light is reflected off his or her face, illuminating us and our path, too.
Our encouraging words needn’t be poetically perfect, like psalms. They needn’t be lengthy or eloquent or profound. Just simple statements. Even a single one.
“All is in G-d’s hands for the good.”
“G-d is wiser and kinder than we are.”
“Nothing ever separates us from G-d.”
“What G-d wants for us is better than what we want for ourselves.”
It seems to me that emunah really hangs on one thing: feeling that G-d is good.
A single moment of feeling that G-d is “good” — that what G-d does is “good” — and we spontaneously let go of the problem. It lifts our hearts to a light and peace that all the mental effort in the world can never give us.
We needn’t even really “believe” that G-d is good. Just considering the possibility — dayyenu.
G-d’s goodness isn’t a matter of “reason.” To feel it is to go beyond “reason,” beyond the way things appear, to a part of ourselves that’s never disturbed by outer conditions.
Of course, we have to be delicate in our encouragement. Sometimes, when a friend is discouraged or unhappy, “positive” words are the least welcome ones! At those times, we can allow our friend to ventilate his or her unhappy feelings to us, while affirming good things of G-d in our own minds and hearts. Doing so, we can radiate a loving, kind acceptance that “reflects” — as it were — G-d’s own.
At the same time, we can find ourselves comforted, soothed, and uplifted by the simple encouragements we’re giving to another, just by allowing G-d’s soothing, loving Light to express itself — however plainly or imperfectly — through us.