Here is a technique for text that I use that may help you. I assume you are using PS.
But I think you can do something similar if using GIMP.
1. For each text layer shift+ctrl select the layer. This will create a selection and also add to the current selection.
2. Once you have selected all the text layers as one selection, create a new layer with a layer mask that is the current text selections.
3. Since it is a mask you can now color fill the layer with any color you want and only the masked text selection will show.
4. Now, you can alt+click on the layer mask and the screen will be black and white. You can apply a filer to this mask for a variety of effects.
5. Then on the mask apply filter>brush>sponge set the parameters as you will.
6. To the mask apply filter>blur>g. blurr at somewhere between 4-8 px.
7. To the mask apply Image>adjustments>levels try to make the mask as sharp as possible. Depending on your dpi I make sure that image size is 100% or 120%.
Now you have some neat looking text, and since it is on a color fill layer you can change the color all you want, add any layer blending effects and layer styles you'd like to. Also make sure the original text layers are hidden, but don't erase them in case you want to modify some the text. Of course you would have to make changes to the layer text mask each time. (That's one downside to this technique.) Also you may want to re-order the text so that it is lower than the parchment layer, that way the text looks like it belongs on the parchment.
One other thing that I don't think was mentioned by anyone else yet. Try adding a stroke to the land. Make it the same color as the lines/brushes for the mountains and stuff and with the same blending mode as those layers. I would go at 2 px or so.
Overall good stuff. Hope this helps.