In GW1, the black holes are usually better off destroyed. It won't help you get more points, just give you another task. Get rid of them as soon as you can. The only way to get points faster in this game is to keep killing enemies to increase your multiplier. In this game, your multiplier resets if you die. Basically, if you're intent on getting the achievements, make good use of your bombs (just don't run out) until you get to the 1 million mark without dying. That, and practice, practice, practice.
For a visual aid, check out this no-bombs video I made. Basically, I played as far as I could without using bombs. The key to note here is, other than noting my strategies, every time I die in the video is a point at which you should bomb :)
VIDEO LINK
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