Ok, I ll try to explain this...........
I am going to assume that you don't know how to get a reliable sit (for the sake of argument only) please don't be offended, I am going to take this to the first level of training.
Make up a batch of Trial Mix for Dogs, all pieces should be very small, use cheese, homemake soft baked liver, dog food kibble, roast chicken/beef etc. As you train, you will figure out which rewards your dog values. When I bake the rewards, my dogs are underfoot, if its something they REALLY like, its just faster and easier to have them out of the room, in the yard or crated lol.
You ll need about 1 cups worth per training session. You can use a bait bag, fanny pack or your pocket, but don't hold the rewards in your hand. Train in your home to start with where there are little or no distractions.
Start by teaching Watch Me or by saying her name. When your dog even starts to look at you, say Yes!! (clicker works great for all this instead) and give your dog a reward (at first it could be anything that you pick out of the bag). In the beginning you mark (yes or click or both) and reward at a high rate one per 2-3 seconds while your dog is continuing to make eye contact. If she looks away, it could be because she has been distracted or you are not reinforcing fast enough. Same methods are used for sit,down, etc.
If your dog were to give you a fast snappy sit, you would give a highly valued reward. If you got a slow sit (this is assuming the dog knows how to sit on cue, either by verbal or hand signal) then you would give just a piece of dog food kibble. We try not to have the rewards in our hands, or if we do with quickly fade it to being in the bait bag/pocket etc. Because dogs are famous for taking the attitude of 'produce it first before I'll do as you ask', thats called Luring. Get the behaviour first, then reward, don't lure if possible.
When training its the Three D's for all desired behaviours, Duration, Distance and Distractions in that order. At any time you start training for any of the above, increase the rewards. Once you have a desired behaviour use variable rewards, the dog never knows what it will get or when, including jackpot rewards.
In the beginning try to keep the distractions low, your success rate will be higher. This is why going to puppy/adult obedience classes are so difficult at first. The distractions are many and it is so hard for a pup/dog to learn. All those smells!! other pups/dogs that can be excited or scared plus strange people and all that is combined in a strange place. No wonder it takes a bit for the training to start to be effective.
Keep your expectations realistic and fair to your dog, make it fun and DON'T get frustrated because your dog will feel your stress and think that THEY are doing something wrong.
And yes, use *gold rewards* when training in a new place, working on a behaviour that your dog already knows and knows reliably at home etc.
I stash goodies (rewards) in several different places in my home, I put them in Zip lock baggies or Plastic containers with lids. I only put a few in each, its better to restock everyday than to have stuff rotting (if you don't use it and forget its there!! ) not only would it become stinky, IF the dogs managed to get it, they could get sick.
Take care and good luck
Lynn