Not a professional renderer-maker-oonie, but here's my 2 cents:
Inventor Studio is still very bad (might be better in 2019, but I haven't tested it myself. I wouldn't hold my breath). Download Fusion 360. Model in Inventor, export as .stp and setup your scene in Fusion (or basically any other software, but Fusion is free, so...). Autodesk Showcase was the absolute bomb for making fast renders, but in the worst move since invading Rusia in winter, Autodesk abandonded it.
If you really want to use Inventor, there is not much to explain (unless you want to animate stuff), because there's just not a lot of options. Experiment with the studio lighting styles, this will make the most noticeable changes to your image. You can add fixed camera positions but they are hard to "visualize" what your final image will look like. I personally haven't found a decent use for them. You can also add extra lights, spots, beams, what have you, but the tool for them is absolute garbage. It's not impossible to make a decent render with Inventor Studio, but it's not worth the hassle imho.
Standard the renderer is set to "Render by Iteration". Don't do this as there's no way of knowing how long it will take. I personally use "until satisfactory", so I can leave it for as long as I like (or abort if it turns out fugly again).
The things that will have the most impact on needed render time are, in no particular order:
-resolution of output image (under render image->general)
-lighting and material accuracy (under render image-> renderer)
-Image filtering (they're listed from fastest to slowest basically. Unsurprisingly, the slowest will yield better results. I wouldn't bother using anything other than Gaussian, unless you are making images for promotional purposes. In which case you wouldn't be using Inventor Studio anyway)
I hate to **** on Inventor, because I actually love it and use it daily. It's an awesome parametric modeller. But a very crappy renderer.