Lots of good advice here - I've had 3 sections. (one was an emergency so I have a scar from my navel downwards, and 2 normal scars)
The hospital will get you out of bed after the first 12 hours, do not object, take it at your pace and do remember to stand really straight up, more than you would normally do, this prevents the scar from healing 'puckered' and allows it to stretch.
Big pants are a good idea to keep any padding there against the scar (especially good if you already have a toddler as their head is the height of your scar) ouch!
Take a cushion for the journey home in the car, I put mine under the seat-belt against my tum to soften any bounces.
I was quite sick after my surgery (I'm allergic to Morphine) top tip is if you sneeze/vomit/cough to bend forward and put your hands against the scar to give it support.
The docs will also tell you not to drive for 6 weeks - DO NOT DRIVE unless its an emergency - pushing down on the pedals in the car put unnecessary pressure on your abdominals and can give you problems in the future.
I found that sleeping flat was the best thing for me, other ladies in the ward had the beds propped up and found that the muscles had 'shortened' and they found standing really painful.
Keep moving as much as you can - rest when you need to but dont take to the sofa - for me it kept the fluid in my feet away and the scar was ok after about 11 days. so much so that we went from Wales for North Devon for the day! (shock)
I also found still wearing my maternity clothes for a few weeks after was good as the waistband was higher and allowed for stitches to heal.
Good luck. (smile)