Lamar Odom's battle with drugs, alcohol and depression almost cost him everything -- so he's telling Johnny Manziel the #1 thing he's gotta do to avoid the same traps.
"Put higher power first," Odom told TMZ Sports, "Whoever his God may be."
Lamar, of course, was in a coma for days after OD'ing at a brothel in Nevada ... but he continues to party hard despite his brush with death.
Johnny, meanwhile, says he's got his life back on track ... after years of hitting the bottle while he struggled with bipolar disorder.
Lamar doesn't want him to go through that pain again -- telling us he's a big-time Johnny Football fan ... and that he truly believes JM can make an NFL comeback.
But Odom says work's gotta be put in off the field, too ... with a focus on faith.