Firstly, welcome to the boards!
My main piece of advice is to try and establish your style. Look around at some other mocs around here and see what you like, maybe try to experiment a bit yourself. Also don’t be afraid to make changes after it’s posted, Some of my mocs have been through many iterations and I still haven’t posted my final design. Take people’s feedback on board but use it as a guideline rather than the be-all-end-all.
Also, are you going for quality or quantity? If you want to make a load of mocs in one go, I’d suggest using standard Mata/Metru/Inika builds as a base and adding some slight variation. If you want to make your own unique character but don’t mind taking longer to make it, then a custom build is your best bet. I’ve got plenty of custom torsos to look at, and plenty of other users do to. As I said earlier, have a good look on the forums for some inspiration and I’m sure you’ll come up with some ideas.
Some advice specifically for Studio, get all the part packs. The site you linked has some good ones, though the biopack is outdated, the new version can be found here, and also has links to some some colour packs to make your renders look nicer. On the subject of renders, here’s a link to some backgrounds to go with them.
On another note, I like the use of purple for lightning, I have to say I’m not much of a fan of some of the canon colour schemes for some elements so it’s nice to see some variation there.