Since I mostly go by physical evidence I write down all of the physicals as symbols at the bottom with a circle for: left, heavy, female, curly and a square around for: right, slim, male and straight. Then I question motives till I have all the suspects, 11 for my difficulty level.
I write down the first 3 letters of each suspects name. Then I check my research and put a circled T for cleared by the cleared persons' name. I then go through each persons alibi from the top. If I hit someone with a false alibi I check all the evidence against them and put a line through their name if I clear them. If my physical witnesses clam up I go through the other witnesses and put a 0 to the left of those who know nothing and an exclamation point beside those who have a suspect in mind. Then I question my suspects about those with no alibis starting at the top of those not cleared.
If I manage to ask all but 1 of the witnesses about a suspect I can cross them off. I put an X through the dead suspects. I put a little fraction next to each suspect who clams up on me to remind me who I asked them about (eg. 1/3, 2/3, 2/2, 0/2). This works because I always ask in the same order. If all my suspects clam up on me I guess. I've guessed wrong twice now and they were both notetaking errors.
Of course it 99/100 times it never gets this far. I usually find my killer before I even know half their alibis.