I was a bad dog.
Maybe I should explain. My sister, at age six, wanted a dog badly. To demonstrate that she would be able to take care of a pet, she decided to train her four-year-old younger brother-me. She would teach me a "trick" and then give me a Cheerio as a reward. Things were going well until she tried to teach me "wait". The idea was that she would put a Cheerio in front of me and tell me to wait. If I didn't immediately eat the thing, she would give me another treat. Unfortunately, whenever she put down the treat in front of me, it was devoured before further instructions.
This resulted in a loss for both of us: she never learned how to properly train a pet and I didn't realize that I could have gotten even more Cheerios- alas. When we think about our plan in notrump, we should be wary of grabbing the things right in front of us; waiting will yield us better results.
Planning the play at notrump can seem either impossible or incredibly simple. The trick to getting to the point where you welcome notrump contracts with open arms is to take a methodical approach to the hand. Approach every notrump hand the same.
Our plan will be three steps: 1) Count winners 2) Look for more possible winners 3) Evaluate the stopper situation
Counting winners: The first step is to count our sure tricks. Sure tricks are tricks that are there for the taking without any work. If we have an Ace, that is a trick we can take at any time. If we have the Ace and also the King that will be two sure tricks. For instance: AKQ is three sure tricks. AKJ is two sure tricks. AQJ is one sure trick. KQJ is ZERO sure tricks. It can become two tricks for us if we develop the suit by playing it.
Counting winners at trick one allows us to know what work we need to do to make our contract.
Contract: 7NT. The lead is the 
J. Plan the play.
Do you take the finesse? If you count winners at trick one, you'll know better. You have 4 heart tricks, 4 diamond tricks, and 4 club tricks. That means you only need one spade trick.
Too often, people play from dummy without thinking about the whole hand.
Step 2) Look for more possible winners. While we may have enough tricks for our contract at the outset, we still want to take as many tricks as possible. Often, we'll try to set up our longest suit, and that's not a bad default. Sometimes other suits will yield lots of tricks relatively quickly (KQJ10 opposite 32 is a suit that can set up 3 tricks relatively quickly). This is our pivotal step to earning higher scores.
Contract: 3NT. Lead: 
J
Here we count our sure tricks: 2 spades (AK), 3 hearts (AKQ), 0 diamonds and 3 clubs (AKQ). 8 total. We need one more trick to make our contract. Though we only need one more trick, more is always better. Diamonds can be set up to take 3 tricks- if we play on diamonds our opponents will take the A and K, but we'll take the rest, giving us 11 total tricks.
Step 3) Evaluate the stoppers. A stopper is our way of preventing the opponents from running a suit. Sometimes we have A and K in a suit, sometimes we have holdings that will prevent our opponents from attacking a suit like Kxx opposite Qxx, and sometimes we won't have any stoppers in a suit. We have to decide if our opponents can take a lot of tricks before we will have set up the suits we want to. Consider hand 2 again. On the lead of the J we have two stoppers in spades, three in hearts, and if we win the club trick we will have two left there. That means if we lose the lead twice our opponents can't run any suit successfully, so it is safe to go for our diamonds.
Instead, let's say the lead is the Q. Now we will only have one spade stopper after the first trick. That means if our opponents win a diamond and play spades, we will be able to stop them once, but not twice. When we knock out the A or K, they play a spade and we have no more protection. Now we play another diamond and they take AT LEAST three more spade tricks.
Instead we can look for other ways to take 9 tricks. Here we have 7 clubs total, if they split 3-3 we could get an extra trick and make our contract. Note that we didn't try this when a club was led, because our ability to set up three diamond tricks meant that we would take 11 tricks (losing only the two diamonds). If we had tried the clubs first and found out that they are split 4-2, we would lose two diamonds and a club.
For more information about this topic, you can purchase "Larry Teaches Declarer Play at Notrump"
