Mechanisms to promote positive ecology

I've only been able to come up with four:

(1) Voluntary: Producers/companies voluntarily adjust their outputs and means of production in favor of what they deem environmentally responsible. This isn't promoted in the free market, it makes them uncompetitive unless there is a demand for their products by educated consumers due to their practices.
(2) Consumer demand/activism: This kind of meshes in with the former one. Consumer-activists macroscopically place demand on products that are created in an ecologically "ethical" fashion. This would require an unheard sense of consumer awareness (as well as a popular demand for environmentally "ethical" practices) and probably some transparency on the part of producers.
(3) Legal restrictions: Governments formally place restrictions on producers/companies and designate land for environmental purposes to be excluded from the market (state-owned). I guess I could see private projects akin to "national parks" but I think it would be generally easier to approach the matter governmentally.
(4) Green taxes: Externalities are somehow incorporated into production costs through taxes. Wow- this would be hard.. but not impossible.

So as to which one or combination of these would be the most favorable, I think (1) can be ruled out for the reasons given--voluntary consideration could happen in an ideal world, but not a modern capitalist one... unless green taxes were in the picture and kicking.

I'm kind of thinking (2).. but that would be a hardcore grassroots effort. And then of course, land management would undoubtedly need to be handled through the state.

I need to narrow my focus to decide between formal (legal restrictions/taxes) and social means. I'm not sure on what grounds they should be judged. If anyone has any suggestions I'm open to them, if not I'll address it whenever I dig myself out of the hole I just made.