Most tutorials for the Source Engine were hosted on the Facepunch forums which no longer exist. The rest are either part of the Valve Developer Community Wiki or as steam community guides for various source games. Namely Garrys Mod and Source Filmmaker.
Those should be enough for making models. Making nice looking models is asking for a lot. The material system for Source is extraordinarily cryptic, inflexible, and unfriendly.
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To save you some time here's some mandatory resources.
You'll need vtfedit133 at the bottom of this list for texture creation.
http://nemesis.thewavelength.net/files/files/
For baking normalmaps synced to Source use either Handplane or Handplane Baker.
http://www.handplane3d.com/
To export the smd model format used for compiling models pick one of the following.
3DS Max: https://knockout.chat/thread/806/1
Maya: https://puppet-master.net/plugins/mesa-2-0/
Blender: http://steamreview.org/BlenderSourceTools/
These cover the bulk of model and material creation.
https://developer.valvesoftware.com/wiki/Category:QC_Commands
https://developer.valvesoftware.com/wiki/Category:Material_System
https://developer.valvesoftware.com/wiki/Category:List_of_Shader_Parameters
Those should be enough for making models. Making nice looking models is asking for a lot. The material system for Source is extraordinarily cryptic, inflexible, and unfriendly.