When working with beginning cooks, the most common inefficiency I see is in task planning. Say you've got four onions that need to be peeled, finely diced, and transferred to a large bowl. If you do each of these steps to each onion one at a time, you spend a lot of time moving back and forth between the board, the compost bin, and the bowl, picking up and putting down your knife, and mentally preparing yourself for the next task.
Instead, work like a factory: start by cutting off the end and splitting all of the onions. Next peel all of the onions. Then make all of your horizontal cuts, followed by all of your vertical cuts. Finally, transfer all of your perfect dice to the bowl and clean down your board and countertop before you move on to the next task.
Apply this kind of thinking to all of your tasks and you'll find that the time you spend in the kitchen will not only be more efficient, but also neater, cleaner, and more organized.