The even more important 'golden rule' to remember is to not house 2 males in any enclosure. A green anole male and a brown anole will fight even though they are different species. Don't do it unless you want an injured or dead anole. You can have multiple females from both species though.
If you have to ask about mixing species, don't do it! It's common to have brown and green anoles together and even to have green tree frogs with them but do not consider the 2 jeweled curly tail lizards. You may have had successful 'mixed' terrariums in the past but you can never be 100% sure that the animals weren't stressed. Where is the mixed tank at now or do you still have it? Why put anything through the stress? Putting them together for your own amusement isn't fair to them. If you want to look like a caring owner than you should house them seperately.
With anoles you can use a wide variety of substrates. Just don't use sand, bark, or crushed walnut shells. If you use bark layer a thin layer of moss over it so that if an anole accidentally gets something in its mouth while feeding it'll most likely be the more digestable moss instead of the indigestable bark. If you want something more natural than sterile soil is the way to go.