Give some examples of things that can be done to reduce the human impact on the environment, either as people or companies.

I'll give you a place to begin with a Top Five list of things to
do (or not do) that can reduce the footprint we leave on the
planet:

1)  Consume less - this is especially true in America, where
each person consumes many more resources than they should.  We can easily and safely use less
water, less gasoline, less electricity and we can buy less.  These are simple changes in our
daily habits that both save us money and benefit the
environment.

2)  Reduce our waste - We have become a disposable
society, where eating one fast food meal produces paper bags, napkins, wrappers, straws, cups,
etc., all for one meal.  Eating out once per week instead of three times, for example, reduces
such waste by 2/3.  Much of what we throw away can be recycled or
composted.

3)  Practice the saying "I don't need a bag for that". 
The tendency to put every single purchase, no matter how small, in a plastic bag is both
unnecessary and wasteful.  We don't have to be complicit by carrying them out of the
store.

4)  Companies can invest in energy conservation.  Sensors
that turn off lights when there is no movement in a room, public bathrooms that minimize water
usage, insulation and solar panels all can be green friendly ways a large company can both make a
difference and set an example.

5)  Cut down on packaging use -
Companies can request that the items they are sold not come in heavy duty plastic packaging,
that, while saving a little money in product loss/shoplifting, costs quite a bit and greatly
increases the amount of waste that comes with sales.  We used to get by with much less, and can
do so again.