Are you scuplting everything within Blender, or do you have a separate program such as Mudbox or ZBrush?
Usually the meshes that come back from those programs (and even in blender’s sculpt tool) get sculpted at as high poly as possible to keep the details. To get the best results, you will want to create a somewhat lower poly mesh of the same model. Do not worry that some of the detail get’s lost, as you will be baking this information onto a normal map. Export out both the high and low poly versions of the mesh to a folder.
Do not worry about the detail being missing, we will now bake that info into the mesh. Download and install xNormal .
When it opens up click on the “High Poly” tab, and load your High poly mesh into the first slot. Now go to the Low Poly section, and choose your low poly mesh.
Next click on the Baking Options button, in the top box, you want to enter a folder to save all output to, also choose a size (2048x2048 should be enough). Now in the “Maps to Render” make sure ONLY Normal map is selected.
Now all you need to do is click Generate Maps button on the bottom right, this will output a normal map texture to the folder you specified. If you now import both the low poly and the normal map, and create a basic material. Make sure to plug your normal map into the normal slot, save the material and apply it to the mesh you imported.
This should give you an idea of how to keep details on the model surface while using the lowest number of tri’s possible.
Let me know if any of that doesn’t make sense, but I can assure that this will work with fewer poly’s (1k poly’s is a bit too low, as you get better at normal mapping it may be possible, but in this case even if we can cut the poly count in half, it will make a big difference.
Hope that helps, let me know if you need any assistance.