Yes you paint it first. Use the color you like best. I used True Blue craft paint in a project I did several years ago.I am going to recommend a product from Woodland Scenic. Realistic Water and Water effects are brand names from Woodland Scenic. I have some WIP photos from a non LOTR projects I will use to illustrate.
Create the base model and paint it. The model should be completely dry.
I used green for this game tile but Like I said use dark blue and highlight with sky blue for normal LOTR base. Use dark colors to give the appearance of depth. When the paint is dry add a very thin layer of Realistic Water. Put it aside and do not touch it for 24 hours. The instructions suggest 12 hours.Trust me wait 24.
Add the Water Effects to the Realistic Water. You will want to practice a bit on a sheet of clear plastic. The Water Effect will peal off of the plastic when it drys. This is a good way to make waterfalls and rapids.
You will want to wait a few hours and let the Water Effects set before adding layers. Do not let it get too thick or it will takes weeks to dry.
Even though the Water Effect looked dry you can see that some moisture was still present when I added the next layer.If you use thin layers of Realistic Water this will disappear. Note also I added some grass to the model before I added the final layer of Realistic Water. Do not wait for the white glue to dry. The PVA will prevent the Realistic water from spoiling the grass. I used Water Effect as Glue. It will dry clear
The waterfall for this set. I used Stillwater on the cavern river tile, It dulls over time. I like Realistic Water better.
The Bog of Eternal Stench.
"The air is sweet and none shall pass without my permission"
"Go Back or you shall meet your doom!"