So for me, when I'm doing weathering on anything, I try and look at how the character moves, what they do for a living, and where they do it at. Since you've mentioned that you're envisioning a starship mechanic, we at least have a place to start. Most of your weathering would then come from welding sparks, hydraulic fluid, and the occasional rip from a sharp metal edge. To simulate some of this, you could get a piece of metal bar from a hardware store and use an angle grinder to give you a shower of sparks over top your flightsuit. You could also take a wire brush wheel to simulate years of sliding around on hands and knees. For my kama, I used a hammer to strike at it in different angles to get wear and tear, so that could work as well. Hydraulic fluid is going to depend on the colour of the flightsuit, but you could use old motor oil or drip some WD-40 on the fabric to give it that authentic look. If you go that route, I'd strongly encourage that you do it after you do any burn weathering to avoid any possible flambe de Mando'ad. You can also use weathering powders, chalk, and spraypaint to achieve good weathering. Scratches can easily be simulated by dipping a brass wire tile brush in a little bit of paint and dragging it across the plates, or you can do the same with a steel brush if you basecoated everything in a metallic colour and before you clearcoat your top layer. Try and keep in mind what would be natural for the character, since that will affect your placement of weathering.
All that being said, I would heartily encourage you to focus on getting your OM approval first, then do your brigades upgrades. It'll give you milestones to checkpoint at, and it'll give you a chance to get comfortable with the materials.
Hope this helps you out, ner vod. Cheers!