From experience:
If you have more than one rooster in your flock, avoid removing the rooster. Even for a vet visit. The fights for reintroduction were brutal.
I treat my birds after they go to bed. Much easier to catch.
Have your station ready. Table, bandages/vet wrap pre-cut, Neosporin, pads/goze, tweezers, scissors, antibacterial spray...everything ready and within reach.
Have a large towel laid out.
Best if someone helps you.
When I have to treat feet by myself, I place the rooster on the towel but keep it close to my body. That way one wing is trapped between us. I lean over and once his side pined to the table, I quickly pull the towel over him. I then try to wedge him under my arm and next to my side. Think elbow on the table and him in the triangle space of table, arm and your side.
I can usually angle the pinning hand to hold a foot and use the other to clean and treat the foot.
When I soak feet, I usually do it in the small half bath.
My boys, I have 5, are pretty cooperative. Sometimes I have to hold them in place in the sink until they relax. I can get them to chill in the sink for 15-20 minutes. The soak helps soften and pre-clean the feet.
I try to remove scab and use tweezers to find the kernel.
Vet wrap:
I like to use the 2 inch wide ones. Depending on size of bird I cut 3 4 to 6 inch long strips. Two of the strip I fold in half. This doubles them. One goes between the middle and outside toe across the pad and behind the back toe. The extra length goes next to the shank. I place the other one between the other open toes. This makes an x. I then use the wide strip to secure the ends around the shank.
The hand that holds the foot: I usually have the shank between my middle and ring figure. I use my index finger to spread open toes. Thumb to hold medical and bandage in place.