Bubbler sounds like it'd be the hardest, since all three levels are very different from each other. Ultimately it's up to you, I don't have any recommendations. Oh, I just realized that I probably won't need to ask you anymore to make weapons for me if I can follow your guide easily enough! That's nice.
One question I just have to ask for OllyDbg: how do I make the code / interface bigger? It really strains my eyes because the normal size is kinda small.