Top 3 Do's
1) Seems obvious enough, but when you are asked a question, answer it! Voters are not stupid - they know when you are evading an issue and it does not work to your advantage. Sometimes, it's even OK to say "I don't know, but I will get back to you." Really, it's OK. Honesty - it's a good thing and (sadly) will likely differentiate you from others.
2) Offer specific solutions to current issues. The time for platitudes is long over - voter's don't want to hear them. If you don't have specific solutions to offer, get to work and develop them! Voter's are short on patience!
3) It's the economy, stupid. This has never been more true than now, at every level of government. While you may be passionate about a variety of social issues, voters' top concern is the economy and the associated issue of government spending. Focus on the financial issues that are most important to, not only GOP voters, but also those all important independents.
The "Don't"
So, according to Newt, asking about his disintegrating campaign was a "gotcha" question. And, apparently, asking about his position on Libya was, as well. Really, Newt? While we have a lot of respect for the former Speaker and for many of his ideas, this tactic is one that diminished him. And, unless you are at least of the equivalent political stature, it is likely to diminish you even further.
Both questions were legitimate and his "I'm smarter than you" attitude to deflect something he couldn't defend did not fool many. Just made him look desperate. Better to answer directly and succinctly and move on to something else. This approach just calls more attention to something that you'd like to go away.