Visit in April when the weather is best. The first two weeks are lovely!
Make sure you take a jacket with you if you are staying out late on days out. The temperature can drop quite a bit in the evening.
Try and learn a few Chinese phrases if you can! It will help you. Way more than you can imagine.
Make sure you have the addresses of the places you want to visit written in Chinese lettering in case you get a taxi.
If you have a chance to visit the Radisson Hotel at the edge of People's Park take the lift up to the 45th floor for a great 360 degree view of Shanghai.
Walk down the Bund at night for a magical view of the Oriental Pearl Tower and take a good camera. It's definitely a picture moment.
Visit the old abbatoir, called 1933, for an interesting look at an old art deco abattoir which now hosts a creative hub of restaurants, retail, art and design companies.
If you are into fabric and clothes visit the fabric markets and make use of the great tailor services to get some clothes made.
There is also amazing haberdashery market available which has a huge selection of ribbons, buttons, braids and trimmings at competitive prices.
To travel between the cities I recommend the overnight sleeper train, which isn't too expensive.
It's very comfortable and a great experience if you want to make the most of your time. Waking up in your next city is a great way to start your day.
If you want to visit the Great wall of China make sure you have some comfortable shoes for walking and definitely don't forget your camera and a coat to keep you warm.
I recommend getting the cable car up to the top of the wall to save time and for fun you can get a toboggan down to the bottom.
That's just a small bunch of tips.
The biggest tip is to take a travel guide, like my smart travelling companion did or to install an app on your phone! But just don't rely on it for everything. ALWAYS carry a tourist map available from Tourist offices for up to date info.
Trip Advisor does a pretty good app for each city, which has lots of restaurants and places to visit listed.