First of all you could refer to this forum

in my point of view,try to make the wheel first since its supposedly be the easiest part of the landing gear and that you're gonna mostly copy paste them anyway. 



basically most wheels are just a shape of circle stacked on top of each other, with varying size, colors, & effects. you could also add some 'dent' to the bottom of the wheel to visualize weight or so, but this example of mine is sorta bit overexaggerated, just give a small pinch. after you're done with the wheel, you can start doing the other parts.

first just try to make the basic shapes of the structure first.
if you got the blueprint/schematic, nice; if you don't, just try to eyeball it with some close ups photo or walkarounds.



Seconds, Adds some details.
using visual reference such as close ups photo or walkarounds is a great helper.


Last add the effects and blings.
assuming you already know how to lightings & reflection or so.



one other thing to say is, you dont really have detailed to the point or even as detailed as my example here (unless you're up to that, your choice). As long as it's look good zoom out you're good in my opinion.


if you're interested for a file for this landing gear i have, hit me up in the dms. 
hope this helps, cheers.