Smith was called to step in for Kevin Glenn after he injured his shoulder during the game against the Hamilton Tiger-Cats on Sunday.
But Smith, the star quarterback of his high school team, missed passes, got sacked and had trouble scraping together a first down.
Joseph has been in Smith's position before, but he turned his first start into a 12-year career in the CFL.
"My advice to him is let the game come to him. Trust his eyes. Trust his instincts and just play. The worst thing you can do is try to hold back and not make a mistake," said Joseph.
"That's when you make them."
Game can become blur for rookies
He said for rookies like Smith, once on the field, the game can quickly turn into a blur, and it causes quarterbacks to miss key opportunities.
"As a veteran, you have seen so many things over the years, and you have been around so many defensive coordinators that you are accustomed to what they call," said Joseph.
"As a young quarterback, sometimes it doesn't happen that way and the game just continues to move too fast for you and you have to wait and slow your eyes down."
Joseph says the best way to deal with that is through preparation and good coaching like he had.
"You have to break the field down. You have to break the defense down. That field is 65 yards wide, and if you try to look at the whole field, you're not going to see everything. And they taught me how to compartmentalize different plays," said Joseph.
Starting a game more difficult
Joseph said starting a game will be much more difficult for Smith, rather than coming in mid-way through.
"Coming into the game, coaches are going to game plan against you now. Being a young quarterback, he can expect to be pressured," said Joseph.
"They are going to try to confuse him, and that's one thing he can be prepared for."
The good thing, said Joseph, is Smith will be surrounded by veteran players like Chris Getzlaf, Weston Dressler and Jerome Messam.
He said that should help Smith to feel less pressure to carry the weight of the game on his shoulders.
But he added that even after this game, Smith will continue to be studied by other teams.
"They are going to find out what he did well and what he didn't do well and they are going to try to attack that. So he is going to have another challenge," said Joseph.
"It takes a couple years before a guy can really get established in that league and get comfortable with a team and what different defenses are trying to do to you."
The Riders face the Eskimos Friday night in Edmonton. Kick-off is at 7 p.m. CST.