Andy's comments about a minimal set of HTML commands make a lot of sense. One additional trick: If you are typing in a long song, with lots of line breaks, it helps to type it into a word processing file (e.g., Word), and then do a global replace in which you insert the < br > HTML in front of the paragraph breaks. In Word, for instance, this means using the "replace" command to insert the break command before each paragraph mark, that is, convert ^p into < br >^p .
Then copy and paste from the word processing program into mudcat. It's less fiddly than it sounds and saves having to type a lot of < br >'s.