Determine what the candidates personal philosophy and beliefs are beyond what his/her party says (their position) on the issues.
Have they (politician and party) delivered on their last promises, if not why?
What is their position on moral, social or spiritual issues and are their positions compatible with yours?
Measure their words or plans against stated objectives and actual accomplishments (make sure and record/document promises for future comparison) Did they live up to their word? If not ask why and take note before allowing them the opportunity to give another word. Are they transparent. Can you get a straight honest answer or do they ask you to trust them while not giving you information you requested.
Do they purposefully withhold information. What is their track record in leadership. Have they been decisive and true to their word?
Do their policies make your life better in the short or long term?
Have their current policies negatively impacted you?
What are their convictions and do theirs line up with yours (ask specific questions)?
Ask very specific questions: for example do you believe in (blank and you fill in the blank)
Do they know how to prioritize (place most important items as the focus of their agenda)
Have they outlined a vision with specific plans that they can be judged on when in office
Do critics and opposition parties present a viable alternative that is documented and which they can be judged by and evaluated upon (every potential leader should a written vision).