Which preposition should follow "guide" here, "on," "to," or "for"?

Generally speaking, I personally prefer "guide to" over "guide on"; "guide about" sounds rather strange to me (though not ungrammatical).

By the way, mohang's Google results are very different from what I'm seeing:

• "guide to" — 171,000,000
• "guide on" — 6,530,000
• "guide about" — 485,000

(If I add an article in front of "guide" to make sure that I only get results where it is a noun, the picture is the same: 119,000,000 vs 4,730,000 vs 252,000 for "a", and 15,500,000 vs 2,380,000 vs 156,000 for "the".)

I checked the British National Corpus (BNC) and the Corpus of Contemporary American English (COCA), and they both seem to agree:

                   BNC   COCA

guide.[n] to      1419   4553
guide.[n] on        37    194
guide.[n] about      4     15

guide to how        41     27
guide on how         6     16
guide about how      1      1

That being said, as Rocquie points out, two "to"s in rapid succession are not everybody's thing. I actually agree, so in this particular case, I would probably go with "on" (as Bruno suggests) or with "to" + gerund:

• a guide on how to use it
• a guide to using it

The BNC stats look as follows:

guide on how to     6
guide to how to     4
guide about how to  0

guide to using/getting/making     3/4/7
guide on using/getting/making     0/0/0
guide about using/getting/making  0/0/0

Now, what about "guide for"? That one is trickier, because it usually means something else entirely — more often than not, the for denotes the target audience rather than the subject of the guide (though the latter is not unheard of, either). Here are just a few examples from BNC and COCA:

• The Guide for the Perplexed
• A Guide for Married Couples
• a Resource Guide for the Responsible Non-Monogamist
• Evaluating the School: A Guide for Secondary Schools in the Metropolitan Borough of Solihull
• Licensing Digital Content: A Practical Guide for Librarians
• A Green Guide for Travelers
• How to Win an Election: An Ancient Guide for Modern Politicians
• a copy of Practical Guide for Asthmatics

You can't meaningfully substitute to, on or about in any of these examples.