Before baking, it's best to move all the overlaps and mirrored parts outside the 0-1 square. If the mesh uses overlapping UVs, this will likely cause artifacts to appear in the baked map, since the baker will try render each UV shell into the map. Only one copy of the forward-facing UVs should remain in the 0-1 UV square at baking time. Normal map baking tools only capture details within the 0-1 UV square, any UV bits outside this area are ignored. View the finished in-game model and textures in your game engine, and check for errors.See Of Bit Depths, Banding and Normal Maps. See Normal Map Technical Details#Common Swizzle Coordinates. Some errors can be painted out, but avoid this! Any painting must be repeated if the model is re-baked, and painting on a normal map can introduce more artifacts.See RNM Normal Map Combiner, and Combine Normal. Add details from photos or other bakes.See Ambient occlusion map#EarthQuake's Baking Method See Synched Workflow, and Converting Between Spaces. Use object space, if converting to a specific tangent space.Some errors can be painted out later, but avoid this! Any painting must be repeated if the model is re-baked, and painting on a normal map can introduce more artifacts.See Skew you buddy! Making sense of skewed normal map details., and Skewmesh Tutorial. Adjust the bake settings, low-poly model, cage, etc. Use enough edge padding to prevent color bleeding between the UVs.Smaller render sizes, lower anti-aliasing samples, etc. Test the bake settings using lower values for faster iteration.Import the high-resolution model, the low-resolution model, and the cage.Create an inflated copy of the low-resolution model, which encompasses the high-resolution model.Elements can be tagged by some baking tools, so specific low-poly elements will only bake related high-poly elements, this avoids exploding (3ds Max can use Material IDs, etc.). Tools are also available, see Explode script needed (for baking purposes).
The workflow: If the modeling software has animation, you can keyframe the explode to easily reverse it after baking.After the bake, move the pieces back together. Use the same separation for the highpoly model and the lowpoly model. To explode means to separate the non-welded surfaces, mesh elements, Zbrush subtools, etc.Marmoset Toolbag's baking tool avoids the need for exploding the meshes.The reason: Interpenetrating or close-together parts can cause baking artifacts, because neighboring surfaces will capture parts of each other, see Texture Baking#Solving Intersections.Use just enough subdivisions to get a smooth surface at the baking resolution, and no more. If it's a subdivision surface choose an appropriate resolution.Sculpting tools like Zbrush create triangles smaller than the bake pixels, which will increase baking time significantly without actually improving the bake. If it's a sculpt reduce the vertex count to a manageable file size before exporting.Optimize the high-resolution model to speed up bakes, to avoid running out of RAM while baking, and to keep 3d file sizes manageable.See JedTheKrampus on offsetting Mirrored UVs, Texture Baking#UV Coordinates.Duplicate any model parts which reuse the same UV this ensures perfect UV overlap.If creating symmetrical parts, mirror the model.Triangulate before mirroring, to prevent shading errors.See Texture Baking#Triangulation, and Polygon Count#Polygons Vs.Make sure there's enough room between UVs for good edge padding to prevent color bleeding between the UVs.Making sense of hard edges, uvs, normal maps and vertex counts, and Earthquake on separating smoothing groups in the UV. For tangent-space normal mapping, split the UVs for every hard edge (where vertex normals are split, or different smoothing groups are used, same thing).Create good Texture Coordinates for your low-poly model.See Normal_Map_Modeling#Low-Poly_Mesh and Understanding averaged normals and ray projection/Who put waviness in my normal map? and Skew you buddy! Making sense of skewed normal map details. Remove details from the base version of the high-poly model, or use ReTopologyModeling.High-quality bakes require specific modeling techniques, see Normal Map Modeling.Build the source for your normal map, using DigitalSculpting and/or Subdivision Surface Modeling.Test with all the required functionality so you can determine how much detail is required.Create a rough low- to medium-resolution model, and get it into the game.The baking workflow varies for each artist this is a summary of common baking tasks.