By using dustbin in your locality.
I've tried telling people, to stop using polythene and stop throwing here and there for a long time.
But the problem is they don't want to change. They think only their home is the place to be clean, and other places are not theirs, so how does it matter to them.

One more thing, these people have a false ego,which further creates problems.

I think there is only one way, create fear in the minds of people, by not keeping the surroundings clean they are marching towards their death. 
Fear is the only solution. Show them, what their bad attitude is leading to.
People here will only change by the use of force.

Tell small children and make them change, because they will surely listen and change for the good(they don't have the ego problem). Making small children stop litter, will sooner or later stop their parents, relatives and siblings.

1. If you live in an apartment, during festival times when people are together, tell them about segregation of garbage, importance of cleanliness and how their bad attitude is impacting them.

2.On a regular basis, circulate posters making people realise there mistake of littering and causing damage to environment. Make them submerge in regret. Then they will change.

Spread awareness every moment and every second.

Don't forget to not use polythene and segregate garbage. 
Do this, the people whom you change will change others and change will spread. So begin now. 
Cleanliness is the biggest hazard it can also lead to an ebola epidemic.