First, should I always follow these two words with a comma? My instincts tell me so, but I'd like confirmation. Second, I seem to be addicted to using them. In some passages I use them two or three times. I feel like anything used more than once, e.g., "merely", is too much and will annoy the reader. I do my best to catch repititions when reviewing. However, I find "But" and "However" necessary. I can't seem to rephrase things to eliminate them. Occassionally I can use "Yet." (should that also be followed by a comma?) Suggestions?