Defensive riding includes doing things like looking in every car as you pass to see if you can anticipate the drivers moves - position of hands on the wheel and so on. Look at the tops of the front wheels - thats where you see movement first. Look for gaps that cars coming the other way might turn right across you thru. Look in the wing mirrors to see where the driver is looking.
Filter slowly - not much above walking pace so you can stop quickly and if you do hit there is not much momentum. I tend to filter ( left, right or between the lanes depending where there is most room) only when the cars are stationary or almost stationary and looking well ahead at the traffic lights ( or whatever is causing the tailback) to anticipate the cars moving off.
As the cars start to move off slip into line - usually 2/3 of the way across the rear bumper of the car out to the right. Look right thru the car to the car ahead to anticipate slowing or speeding up.
Vans and the like block sightlines. Extra caution required.
Artics and other big trucks - going up the inside is absolutely perilous. Be certain they are not going to move off as you are alongside and if you do get caught as they move off be prepared to bail out and stop - even dive onto the pavement.
No one else is responsible for your safety - you are.