How do I become more time efficient in the kitchen?
Chefs, professional cooks (and experienced home cooks) do a LOT/MOST of the preparation in advance.

They prepare all vegetables in advance (clean, cut, blanched (if necessary).
They prepare all meats and fish in advance (clean, cut...)
They do all sauces in advance.

They have all ingredients at hands and know what ingredients to use for each dish they prepare.

They know how long each ingredient takes to cook (by virtue of experience).

If you have the chance to go to a restaurant with an open kitchen (where you can see the cooks cooking), you will see that they most assemble ingredients prepared in advance; they will usually cook the "protein" and re-heat the vegetables and assemble that on the plate.

The preparation time can be time consuming at first, but with experience you can more or less reduce that to nothing; 
You can cut and chop vegetables as you go in order of cooking time (for example, cut onions, put in pan, cut garlic, put in pan, cut tomatoes put in pan...)

The cooking part is the most important, either hot and fast or not so hot and slow; again, this is dependent on what you want to do; For example, a steak takes a few minutes, while a stew can take up to hours to cook.

For that, recipes are a good starting point; most of them do well in telling you how long it takes to prepare and cook the recipe.

Same thing for the cleaning part; if possible to it in parallel of other tasks, while the tomato sauce is simmering, clean bowls, boards and cutleries; wipe counter tops...

Don't wait up and let dirty dishes pile up (unless you have a nice boy/girl friend that will do the dishes and clean up after you :-) )

Good luck with that.