I am going to give you some bad advice for lack for something better, because I have not found anything better yet, I had a lot of computer parts stored in plastic storage bins, and because of the high humidity and hot and cold temperature swings were I live a lot of the chromed parts and connectors rusted and the chip and other component connectors corroded, I ended up using a small plastic brush along with some white vinegar to clean the more delicate parts, and a small "soft" metal wire brush with some more white vinegar to clean stuff like the back plates, then I used dawn dish soap and water with a plastic brush to clean the entire board, then clean water to wash away the soap, I want to remove any white vinegar, then a hair drier to dry the board, this seams to work, but not very well, and it seems to not clean has much I would like, also I worry about the white vinegar later causing problems.

I have used a dremel with small wire brush to clean some rust. Am not a fan of actually sanding or grinding on the thin metal around serial, parallel ports, etc.
As long as you dilute the Vinegar with water after it should be fine, it is a mild acetic acid but have not found it too useful on rust (for battery corrosion YES!). An Ammonia based product will actually eat rust better than vinegar but then again you need to flush it off well.

gabimor wrote on 2020-05-29, 17:28:

For places which is not reachable by the dremel, I have used cotton swab with polishing compound, which is not efficient as the dremel.

And what about you?

Pretty much. Lots of metal polish, paper towels, old socks and cotton swabs.

I use a "PCB eraser" - a small silicone rubber block with non-metalic abrasive particles. Gets rid of light surface rust, and leaves a "brushed look".
The residual dust gets swept away with a clean (as in never used for painting) one inch/2.5cm paint brush.