When i write blog entries i try to make the title exactly what i think people would type in a search engine. I figure if i turn up in the SERPS for them and my whole title is bold they will be likely to click me.

The thing i was wondering though is do people search using first person terms or do they type in the third person?
e.g.
"What should I do to do if I want to do something"
or
"what you should do if you want to do something?"

Or would "I" and "you" be considered stop words?

I and you are not stop words because you get different results when you include/exclude them from a phrase. I know "what you should do if you want to do something?" is only an example, but I don't think people would be likely to type a phrase in that was that long. Normally my searches consist of 2,3 or 4 words and never use a subject like "you" or "I". In your example I'd search for "something".

I don't think there is a sure shot way to determine whether people type in "I" or "you" in a search engine . I personally don't use words like "I" and "you" while searching for something in a search engine. In general I would say "what you should do if you want to do something?" would be better than "What should I do to do if I want to do something".

Go by what's readable, the tense doesn't matter otherwise, as mentioned above. They are stop words.

I would search for do something or how to do something