what's the actual problem? how old is the dog?
we get people to stand on the lead next to (and I mean right next to) the collar and place the dog in the down (well, place the dog, stand on lead, correct the dog)
Stand upright unless correcting the dog - you are not there to grovel on the floor after all
For sitting / waiting we get people to place the dog in the sit position (hands on dogs hips, press gently) and then wait for a few seconds before walking on - do it randomly on a walk or during the day and the dog will then have to concentrate on you / the commands rather than be in autopilot until it reaches a command - you can add in a few downs on walks too... it keeps them alert and focussed on you (in theory - it takes practice!)
Recall practice is another good one for waiting - place the dog in the sit, face it's nose (almost touching) say "Wait" and step back to the end of the lead (holding it). count to 7, call the dog, get them to sit at your feet looking at you, count to 7, give a treat. Do it 10-20 times a day, 5 times in a row... it'll soon get the message.
That's the general pup training we do at the school.... you could always commit to proper training (obedience, agility and socialisation in one is best) to keep on top of the dog and get her in the place you want her in the pack (at the bottom!).