I use Maxwell a lot, it's a great renderer, I think it's the best out there. It is an odd beast in that Maxwell itself is purely the render engine so if you are only using Moi, you will need to export as something like OBJ and set up your scene with lights, materials etc in Maxwell Studio and that exports to the render engine. I use the plug-in to Cinema 4D which is very well integrated so I never really use Studio.

It gets a bad rap for being slow but to get similar results from any render engine would take a long time, for my workflow it speeds things up a lot compared to Modo or Cinema's renderers. The beauty is that there is no buggering about with endless buttons and sliders to get a decent level of sampling/anti-aliasing etc. Hit render and it will spit out a very grainy render in seconds then keep refining the samples to spit out a more refined render a minute later, and again after another couple of minutes etc etc. I love it for my workflow as I quickly get something acceptable that I can put into Photoshop, After Effects etc and start applying colour corrections or integrating with other elements and leave Maxwell to cook the render further at the same time. After sometimes doing all my post work, I can replace the render with the most refined version and the job's done. You can even stop it, come back months later and let it render further if your deadline forced you to accept something a little grainier than you would have liked. It doesn't mess around asking if you'd like shadows, caustics, depth of field - it's all just on. In fact a common early mistake is that people don't "focus" the render camera and are surprised to get a very blurred image!

The 2 most important rules IMHO:

Build your scene at real scale - a 50mm tall house is going to render oddly, as is a 1000ft long pen. ie: lighting that pen with a 60w light would be akin to lighting a football field with a 60w bulb, you'll just be scratching your head for hours wondering why your renders are so dark.

Never make white materials purely white. Nothing is pure white and a 255 white will reflect all the light that hits it, causing the render to struggle to resolve the scene, which results in excess noise. 225 would be a good start point for a very white sheet of paper.