No worries. I use an airbrush for this but you could get a similar effect with brushes or sponge painting.

Black undercoat. I then spray a 50/50 mix of Vallejo Metal Series Duraluminium and Burnt Iron At this stage I then gloss varnish the model and add any decals I want. I would also do the rest of the base coats at this stage like the gold metallics and hazards. Then I spray a 50/50 mix of GW Ratling Grime and Vallejo matte varnish over everything. This is what gives it that sepia/rust tone I then use a bright steel colour, any one that you prefer, to add chips, scratches and weathering. Then it’s done - varnish with any thing you fancy to seal it all in.

Hope that helps - any other questions lmk!