Thank you for making an effort and contributing to the CF-community! You have the basics down good and should start looking at the things that makes the map look really nice. Play around with different types of forests and groundtextures. You can find a lot of useful stuff at the Catching Features blog. If you have any questions just e-mail Color or any of us experienced converters or check the CF-forum. Gracias!
You can experiment a little more with the vegetation. If some trees are to heavy for upload you can reduce .tga size with Gimp or others common softwares. To get a denser dark green you can edit the forest grid so to have the trees closer to each other