Do not go over board with any dimension of the game.
Do not over produce cars, factories, sales reps, research, etc.
Stick with mid-sized cars for the first two rounds.
It’s ok to close factories only after one turn, but most likely your first factory will hang around for three turns.
Don’t let factories hang around for too long.
Make sure you do compete against other players. Don't use conflict advoidance tactics. If you do not go head to head, you leave the board open to them. You need to get a reasonable number of sales guys on the floor and cars produced so that your competition doesn’t have a monopoly.
Focus on minimizing excessive waste.
Think in terms of profit. “Will this action make me NET money?”
Being in all markets a little is better then being big in one.
Do not discount and advertize on the same lot (there are advance reason but for your first time out).