I have never been actually involved in a riot, but I have travelled through a riot and been subjected to several nights and a couple of days of rioting very near to my then home in London.

These events were a major factor in my decision to leave London.

As others have posted, it is not easy to prep for a riot since the exact location, and the degree of danger are unknown and liable to frequent change.

The best prep is to be someplace else, either by "bugging out" or if in a high risk location, by permanently relocating.
Many riots start when a meeting or march or rally turns violent. I urge avoiding ANY large meeting, march or rally with political or campaigning connections.
My political involvement is limited to voting, And perhaps attending indoor, small local meetings of causes that I support. I would NEVER attend or knowingly go near ANY large rally or march, political, campaigning or otherwise.

At times of tension, I would urge remaining inconspicuous by wearing dull coloured clothing that blends in with the surroundings. Avoid bright colours that might be connected with one side or the other. Avoid anything expensive that might make you a target.
Wear comfortable shoes in order that you can run or walk well, but nothing expensive, unusual or attention attracting.
Don't wear jewellery or carry expensive portable electronics.
Try to be the "person that nobody remembered"
A firearm is of limited use against a mob, but may as well be carried if you lawfully can.

BTW, shall I post a youtube link about the riots to which I refer ? or is discussing any particular riot getting too close to p0litics ?