Best thing is to take her out to 'train' her rather than for a walk i.e. spend time doing what was recommended above, stopping and going back the other way when she pulls. If she likes titbits have something in your hand and get her attention on it. Stop frequently and when she sits praise her and then walk on, using the titbit to keep her attention. If she likes a toy then use that. Most harnesses won't stop her pulling but if you need to get something try a 'Canny Collar' or a 'Halti' which guides the head. They take a little getting used to but if you keep walking forward then they can't get their feet up to scratch them off. When you meet other dogs get her to sit or lie down till they have gone past, praising her all the time and using a reward if she is good.