Attach a trashbag on your backpack to collect trash in and throw it, or empty it, in a bin when passing by.
 

Bring working gloves if you don't want to get dirty.
 

If you have a heavy backpack you can favour from using a garbagepicker. You can easily attach it the same way as your walking sticks.
 

Encourage others to change their bad habits and to stop throwing trash on the ground.
 

Think of what you bring with you and minimize the consumption of trash.