No there really isn't one that is completely helpful unless you already have experience and are lloking to fine tune your abilities for this game series.
You can try
here just go tothe resource section and there are a few. There are also a few more
here and in the forums there, we have about 4-5 models and texture people as well, it is a small group there but we will try our best to help where we can. Problem is most people that do this stuff develope a style that works for them, so well any of these are helpful they are not necessary the only way or the way that will work best for you. Also you may not be using the same tools as them as some of these are 3-4 years old. Same problem for anything you find in a search, they may not be current or using the same thing you are.
All I can sugguest is start with simple shapes and keep adding to them, try the different filters and effects on things until you are sure of what they can do. Then pick apart someone elses work and redo the work on them.
No matter what you do Texturing is the most time consuming part of do this stuff. It can also make or break a mesh, bad textures will make a ugly mesh no matter how good the mesh is, simple meshes can be made to look good by detailing the textures. You will spend hours and hours on this stuff but eventually you will have some basic parts that you can apply to several models (this is also true for 3D modeling, you will make stock parts and import them as needed). People wonder why you use the same textures on several models with only small changes here and there or more details being added to the orginal than before. The simple fact is a simple texture can be over 20 hours worth of work
an example:
this ship is roughly 2 weeks worth of work (39 hours or so) just because of the amount of details that had to be worked out. I made new textures for it but had to move things into the orginal persons spots because I don't really know how to apply textures to a model yet. Also only the saucer was a stock premade texture that only had to be lines up on the model to make it work, but the rest had to be made. Now on the other hand because I did have all this work handy because every texture I make can be used again on other ships, this one is only about 4 hours worth of work:
Why only 4 hours, because I created a new rim for the saucer, new lite maps (for mackie to render with), and added some details to other textures. Now if I had left them all stock premade textures the ship would have been done in about 10 minutes.
So at first it will be a long event but eventually it will be brought done to something more reasonable. Anyways this is not to scare you away but to warn you that it is not an easy thing to do, it does take time. Also it is to let other know that there is allot of work involved in doing this stuff which is why crititism can be taken quite hard at times. Some of us take it better than others but remember is we did spend time on this stuff so at least be nice, suggestions are welcome for most of us but comments like it sucks are never helpful to anyone. It is also a warning that these will be seen if you post work, but usually by ppl that can not do the work themselves.