The 22-year-old's last dismissal came during Reid's caretaker reign towards the end of last season in a 3-2 defeat at Southampton as his frustration again boiled over, resulting in two bookable offences.
But Reid knows Smith needs to stay on the pitch and out of the referee's notebook if Leeds are to benefit throughout what is due to be an important campaign.
"He is a young man, not a boy anymore," said Reid. "He's had problems disciplinary-wise, but we need to see the best of him on the football pitch and that means showing his ability.
"I like aggressive players, but aggression has to be channelled. It's no use harping on about his disciplinary problems, but he has to channel that aggression into playing football because when he does that he is a fine footballer.
"He's got to play with his heart, but he's got to play with his head as well. I'm not talking about taking his enthusiasm away, I'm just saying don't kick people when the ball is not there, and there's a difference."
Smith found the net just nine times last season, although Terry Venables played him out of position in midfield or on the wing.
Reid is hoping both problems will be addressed this season, starting with tomorrow's Elland Road visit of Newcastle as he added: "With playing him up front, which I want to do, it's about trying to get him in the positions to score goals.
"His return wasn't that clever last year, but I don't think you can blame it all on Alan because he was played in a few positions.
"But he is massively important for us. No one man can do it on their own, but Alan Smith is a big influence.
"He's got everything, but predominantly we will be playing him up front and getting ammunition to him.
"We've got to look to feed him and hopefully we will get quality to him and if we do that then we will get goals.''
UNITED (from): Robinson, Kelly, Radebe, Camara, Matteo, Wilcox, Morris, Seth Johnson, Batty, Sakho, Domi, Viduka, Smith, Martyn, Harte, Milner, Lennon.
NEWCASTLE (from): Given, Harper, Hughes, Griffin, Bernard, Woodgate, O'Brien, Bramble, Dyer, Speed, Robert, Solano, Bowyer, Jenas, Shearer, Bellamy, Ameobi, LuaLua.
Ref: Alan Wiley (Burntwood)