If you missed our previous tips, you can find them here:
Little Brother  doesn't speak in clear complete sentences yet, but he is listening and he does understand a whole lot more. Even if your toddler isn't speaking yet, it can't hurt to start communicating your [age-appropriate] expectations.
Before I leave the house, I name 1-2 specific things I expect from each boy. "Behave" is too vague. "Please keep your seat belt on when you're in the shopping cart" is more specific. Then, warn them about the consequence(s) for disobeying. I'll repeat these once we're in the car, and again just before we go into the store.
Effective consequences have a logical connection to the misbehavior. If Little Brother jets off down the aisle and ignores my call to come back, for me, losing the privilege to walk through the store would be the more logical consequence over calling off an outing to the park.
We can't forget to praise our children immediately for what they do well. In so doing, we'll help them recognize what those things are because it may not be clear to them. By our example, they'll also learn how to recognize the efforts of others and praise them.
Discipline with love and not anger.
For me, how I discipline has become more important than when I discipline. If you are feeling flustered or angry when your child misbehaves, wait. Consider how you want to respond. I believe there are ways to help your child relate a consequence with the misbehavior even when the consequence occurs later.
The hope is, by arriving at appropriate consequences in advance [and when we have a cool head] we'll be better prepared to respond with coolness and love when our child does misbehave. This is the hope.