Kill every 133 and 149 you see, and start luring them towards your next targets when they're almost dead (doing this by running two tiles at a time, re-clicking quickly so you don't lose attack turns; this is also how you pick up drops without losing attack turns). 2-5 prayer points is very, very trivial. You're actually spending more money (in terms of opportunity cost) by not using piety on task, so I highly implore you to reconsider, for your sake. I would do this method, but since i spend more time on other sites than on rs, most of my attention doesnt go to rs. And 2-5 points isnt that much, but when you multiply it by 100 (my current task number) that really adds up fast.