With 3.0 I placed ReShade32.dll and ReShade64.dll in "C:\Program Files (x86)\ReShade" and then I extracted the downloaded .zip version of the shaders from
github.com/crosire/reshade-shaders to that same folder (Resulting in a Shaders and Textures subfolder.) you can then optionally open the shader files and set your preferred default values directly or skip this and then use the in-game UI of ReShade 3.0 itself.
When "installing" ReShade 3.0 I simply copied ReShade32.dll and ReShade64.dll to a known compatible game and started it resulting in the creation of the settings files.
I then quit the game and copied the settings files back to the main ReShade folder.
ReShade.ini (or Default.ini if you want to use that.) looks like this:
[General]
BlockInputOutsideOverlay=0
PerformanceMode=1
OverlayKey=113,0,1
TextureSearchPaths=C:\Program Files (x86)\ReShade\Textures
EffectSearchPaths=C:\Program Files (x86)\ReShade\Shaders
CurrentPreset=0
PresetFiles=C:\Program Files (x86)\ReShade\ReShade_Settings.ini
TutorialProgress=4
PreprocessorDefinitions=RESHADE_DEPTH_LINEARIZATION_FAR_PLANE=1000.0,RESHADE_DEPTH_INPUT_IS_UPSIDE_DOWN=0,RESHADE_DEPTH_INPUT_IS_REVERSED=0,RESHADE_DEPTH_INPUT_IS_LOGARITHMIC=0
[Screenshots]
Key=44,0,0
TargetPath=C:\Games
ImageFormat=0
[User Interface]
ColActive=0.200000,0.500000,0.600000
Alpha=0.950000
ColBackground=0.275000,0.275000,0.275000
ColText=0.800000,0.900000,0.900000
ColItemBackground=0.447000,0.447000,0.447000
And ReShade_Settings.ini (Set up in the above file under the Preset= path.) looks like this:
[GLOBAL]
Techniques=SMAA,
Can also contain shader specific settings but I only use it to pre-enable the shaders I want to use with the games I use ReShade which with the current selection of 3.0 compatible shaders is primarily just SMAA itself so for me using a single path for everything works pretty well.
(The SMAA shader file itself is lightly customized with the default settings I want to use otherwise most of those can be defined in the preset ini file as well if you use the in-game config which will save those settings to it.)
For the rest of the games I use ReShade with I simply now just copy over the ReShade.ini settings file along with ReShade32 and ReShade64 .dll and rename the appropriate one to whatever API the game is using which is generally D3D9.dll or DXGI.dll
If needed (In for example Witcher 3 for one example or GTA V for another.) these settings in ReShade.ini can be modified further.
"PreprocessorDefinitions="
Generally by setting logarithmic and inverted for proper depth buffer detection although this is primarily for effects like depth of field or ambient occlusion and any upcoming 3.0 compatible shader requiring depth buffer detection to work properly.