Stretch marks can be made less visible by using a good quality cocoa/shea butter product, if you check the ingredients and there's more than 20 ingredients then you're really not gaining the benefit from any of them.
You can check google for raw cocoa butter or raw shea butter and melt them together and let them harden to form your own 'body butter', if you'd like a full recipe just let me know.
As far as lifting and firming the skin above the breast, I do something called dry brushing regularly. It's where you take a natural bristle brush - usually made from hard plant fibers - and you gently brush your skin starting at your finger tips and up the arm, making sure to go toward the heart, then brush upwards on the breast 8-10 times and do the other arm.
For nice skin all over you can do it on your feet, legs, and stomach as well.
It's important to do the hands and arms first when using this method because it engages the lymphatic system along with firming the skin and exfoliating it at the same time. It only takes about 2 minutes to do in total.
When I did this it took me about a week of doing it once a day before I noticed any difference and about a month after I started doing it was when I could see significant results.