I use various sized circles or ovals made of white matboard, attached to coat hangar wire with black gaffer's tape. For large areas I have a quite large, very flexible card that I can bend into various shapes. Black side down so as not to reflect light back onto the paper, white side up to identify the part of the image to dodge. I do my dodging as part of the main exposure rather than dividing it into segments; the first second or two of the exposure I can identify the right area, then insert the dodger and count the seconds from the audible clicks of the timer.

Burning in is the same general idea: during the main exposure I keep my eyes on the area(s) that need further exposure and the burning card in my hands. As soon as the main exposure is done, I keep my eyes on the paper, move the card into place, start the burning exposure and begin moving the card. A footswitch to start the timer is very helpful.

I also find that split grade printing makes dodging and burning more precise and predictable. For example, burning in a highlight during the soft exposure darkens the highlights much more than surrounding shadows that may not need darkening.