When you make a complete stop, then you have to start over again as if you were driving off from your house. Picking up speed again after slowing down is not really hard. All you have to do is downshift to the right gear. Say you're on 4th, and you slowed down a bit and need to speed up, downshifting to the appropriate gear will be depend on how fast you are going (this is engine speed vs transmission speed). The lower gear you have at a higher speed, the higher the engine revs. It can either be 2nd or 3rd gear, but that depends on the car as well. What's going to happen if you downshifted to a gear that is too low and you're not driving slow enough for that gear, the car will jerk a bit as the transmission speed will try to match the engine speed. You don't really have to downshift to 1st gear unless you're coming really really really slow (like 5 mph) or you come from a complete stop. I suggest you to get clear feel of your car. In no time, you'll be downshifting easily and it will be just second nature to you.