Copying them here from the Wikipedia page of the Game of Life[en.wikipedia.org]:

1. Any live cell with fewer than two live neighbours dies, as if caused by underpopulation.
   
2. Any live cell with two or three live neighbours lives on to the next generation.
   
3. Any live cell with more than three live neighbours dies, as if by overpopulation.
   
4. Any dead cell with exactly three live neighbours becomes a live cell, as if by reproduction.

Meaning in Bacteria you're trying to avoid creating clusters of 2 or more live cells, and try to murder the existing ones :D

• Only use the single cell tool, the rest just wastes points.
  
• Learn to recognise simple shapes (the still lifes and the first three oscillators on the Wikipedia page), and how to get rid of them by adding or taking away a single cell. (Sorry I'm too lazy to screenshot specific examples, but they are really quite easy to figure out.)
  
• On the beginning of levels remove the small easy shapes mentioned in the previous point, then try to remove enough cells from the main formation so that it can't generate live cells any more.
  
• Usually it's best to manipulate the cells while the game is paused, as I found the mouse cursor is very inaccurate in this game.
  
• Most levels are stable, so on colour mode it might be useful to press play in the beginning to observe the main formation's behaviour to locate the "hot zones".
  
• If you f-ck something up, you can always go back to the level select screen, click to the previous/next level, then back - this resets the original level.

It might not be clear, but the only difference between the colour and monochrome modes is that in the colour mode the live cells that have been alive for more than a turn are cyan, while the cells that came alive in the last round are yellow. That's all.

The only reason why the colour mode might be easier is because in that one you only need to get rid of the unstable cells, while in the monochrome mode you have to reduce the number of all live cells under 10.

• Easy mode
  
• "Difference only" OFF - it hides the stable parts of formations, making it more difficult to understand and get rid of them.

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