If you've got the motivation, here's the method that I would use on Rohan cloaks, using that choices of colors.
1- Base with Castellan Green
2- Shade with Agrax
3- Re-apply base color of Castellan to all but the deepest recess area
4- Mix Castellan with Loren Forest 50:50 and highlight
5 - Highlight with pure Loren Forest
6 - Mix Loren Forest with Straken 50:50 and highlight
7 - Final edge Highlight with pure Straken
Yes, it's a lot of steps, but it will be worth it. Each highlight should cover a bit less cloak than the previous one. And most importantly, you must add water to steps 3 thru 7. Usually a 50:50 Water to Paint ratio works best. It will help with the blending of colors, and will help avoid "cartoony" or garish changes from one color to the next.
If this is too many steps for you, you can try it skipping steps 4 and 6, but if you chose to do so, you will need to add more water in steps 3, 5 and 7 and you will likely need to do two watered down, blended coats for those 3 steps.
Good luck