Of course you can ask buddy! I'm delighted to answer 
So in order to get realistic details on a mecha, you need realistic references. I have a large pinterest board where I collect anything from artist paintings of robots, to good mechanical design from industrial equipment, motorbikes, etc. Basically, I mix and match design elements from various sources that I find cool in order to get a mech that looks belieavable.
Second, I am a mechanical engineer by trade. I know from experience that, right now, mechanical designs go far beyond 90% of what passes for "futuristic" in art. For example, take a look at this image. That's not a robot arm from the future, it's a cabinet door hinge for furniture. If our door hinges look like that, we need to step up our collective game when designing mecha! We need to consider chamfers, countersinks, filets, panels, etc. This is why real world reference photos of robotics and mechanical objects are essential to make good, believable mechs, even if you don't need to understand how it works to imitate.
The last thing to get mecha right is design theory, which is closer to "product design" than "mechanical engineering" in nature. This is something that you can learn (for free in youtube videos!) by studying art and graphic design, or through experience. Concepts like big, medium, small, the flow and read of the silhouette, or having recurring leitmotifs in the shape language (in my case, circular engines of a given size, against box-shaped limbs), which gives the right flow to the design.
Finally, to pull it off, your perspective and rendering has to be reasonably correct. I use perspective grids to keep everything in check.
Hope that helps! Don't hesitate to ask if you have any further questions!
