I wouldn't really know where to start - chin-up strength isn't terribly important to me. I just do some chins and do them weighted whenever I feel like it. Because I had a athletic upbringing and physical fitness was important in my schooling, chin-ups were similar to learning the alphabet. In other words, it's not a big deal.
Perhaps others have more suggestions for you but I never found the chin-up to be anything more than a very basic assistance exercise. I've always been more concerned with squats and cleans. At least when for the first 15 years of training.