Tulamben will be a good place to dive for beginner. Try to get in at 5am to see school of bumpedhead parrotfish coming out of their hideout to look for breakfast. Same with brown-marbled groupers. They are big fish.
Another good place to dive around August, especially during full moon is at Crystal Bay in Nusa Penida to see 20' mola-mola (see my avatar). I had 1 day to dive in Crytal Bay in August 31, 2012, before going to Komodo & saw 9 mola-mola in 2 dives there. You can see how big the mola-mola is relative to the 1-foot long emperor anglefish that was busy cleaning the mola-mola's rear end in the picture. However, it's more for experience diver with good guide, because it can be a deep dive, cold & fast current.
I went to >100' deep to get that picture of the mola-mola. As I was getting closer to it, it kept going down passed the maximum depth for 27% Nitrox that I was using. I was at 145' deep, so, I had to ascend right away.
The water temperature was 68 deg.F (20 deg.C). I had to wear 5mm wetsuit & a hood.
Sometimes the down current could be deadly. If you are too far from the coral & in open clear-blue water, you will have problem to swim against the down current & slowly getting sucked into the deep. When you see your bubbles start to go down, you would need to grab on the nearby hard coral to hang on the coral & start to crawl yourself up to the shallow.
For less experience diver, instead of Crystal Bay, you may want to just see manta at manta point.