I'm trying oil paints for the first time. I can't seem to get the streaking or staining I've seen right. Been trying the dot method but when I go over it with the wide brush it all disappears leaving just the oil straeaking but no noticeable color. Am I doing something wrong?

How long are you letting the oil paint stay before going over with the wider brush?

Also, the wider brush should be damp, not super wet so it just feathers away some paint, and blends colors together.

A lot depends on whether you're doing this on a clear gloss over coat or flat base colors.

If you're over coating with a clear gloss before you do the oils, then you'll need to use a VERY light touch with the brush. The clear gloss will shed the oil paint pigments and prevent them from adhering.

If you're doing this over flat base colors (with or without a clear flat overcoat), you'll need to do the opposite and pre-wet the surface with thinners and be more aggressive with the brush. The flat surface will grab the oil paint pigments and hold them, so the oil paint can't be left for long on the surface before brushing out.

Happy modeling,

Do each color separately and let it dry.
Remember as a kid mixing tempura paints art class, every combination always ended up being a muddy brown? I do.
I've seen "tutorials" where the color dots are placed too closely together. There's no way to spread them out thinly enough without running into neighboring color dots,which is ultimately just going to leave you with a brown "filter" or whatever you choose to call it. The more you wipe off, the browner (but also less intense) it gets.
So-do a few yellow dotes first. Let them completely dry. Then do some blue. Then some green. You'll get that effect you're looking for.