SA,

Having sound knowledge of tajweed is essential. Then you have to pace yourself. In the past, I would get slightly irritated (God forgive me) at reciters who sounded as though they were running a marathon of oration. To me, the most beautiful recitation is one where the rules of tajweed are followed and there is some emotion to the recitation (I don't mean like crying and that sort of thing, since that tends to be distracting at times, but simple emotion in the words). For example, if you study the style of Sudais, you find that he manages to hold long verses, without sounding like he is trying to get it all out in one breath.