Masking tape works well, has a nice texture.
I've got 2mm ribbon for modern 1/24 scale aircraft, but that's way over scale for anything smaller.
For the buckles, if it is 1/72, you can just paint them, but for 1/48, wire is ok, but fiddly. If I were you I'd consider getting some PE sets, they are pretty cheap and depending on the brand, usually come with enough for a few aircraft on the one fret.