I would start by checking the links of similar charities.  That way you can see how they are building links and what is working for them.  Then I would move to the Fresh Web Explorer. There you can search mentions of different phrases that have to do with your topic that the charity promotes. You can then build up your network and start reaching out/link building.

You should also check out the blog.  Plenty of posts there about link building and advanced techniques.  You can even go back to the YouMoz Blog and see techniques and information from back in the day.  They are older posts,  but still valuable information none the less.

I would start by checking the links of similar charities.  That way you can see how they are building links and what is working for them.  Then I would move to the Fresh Web Explorer. There you can search mentions of different phrases that have to do with your topic that the charity promotes. You can then build up your network and start reaching out/link building.

You should also check out the blog.  Plenty of posts there about link building and advanced techniques.  You can even go back to the YouMoz Blog and see techniques and information from back in the day.  They are older posts,  but still valuable information none the less.