According to an article, I came across the other day, (link), one of the best ways of making this determination is to score the opportunity. That is, you give the opportunity points for how qualified it is based on the criteria for qualification.
1. If the opportunity has a decision maker, you score the lead a 5; if it does not have a decision maker, you score it a zero;
2. If the opportunity has a recognizable need, want or desire, you score it a 5; if it does not, you score it a zero;
3. If the lead does not have money to complete a purchase decision today, but will have it in 2 weeks, then you might score the opportunity a 2 or 3; if the opportunity has not money now nor in the foreseeable future, you score it a zero.
The whole objective is to score the leads and pass along those leads that score 20 or more on the point scale to sales for “sales attention”.