I generally look at the track record of the individual relative to the advice being given. I have a great deal of respect for people who have actually done the things that they are giving advice about. I have less respect for the "armchair experts" who have plenty of advice to give, but have accomplished very little on their own.
For example, I would always listen to business advice given by a person who had successfully operated one or more businesses in the past. (I may not agree with or follow that advice, but I would at least listen to it.). Along the same lines, I would be much more inclined to take personal fitness advice from someone who was in great shape rather than from someone who was 100 pounds overweight.
I also think that different people have different styles of doing things. Advice coming from someone who has a radically different style than your own can be extremely difficult to implement. Telling a pig that it needs to swim like a duck generally never works.
Michael A. Silva