Grading schemes to encourage effort
One approach is to have a number of clear learning objectives. For example: 


  At the end of this course the student will be able to differentiate functions of a single variable. 


Then for each of these provide a description of what it means to obtain each of the various grades available.


  F: The student does not grasp anything about differentiation.
  D: The student is able to differentiate simple functions.
  C: The student is able to differentiate many functions, but has difficulty with composite functions.
  B: The student is able to differentiate most functions and employ the chain rule.
  A: The student is able to differentiate all functions and can apply first principles.
  A+: The student employs novel approaches to differentiation.


Of course, you'd need to tailor these to your course and make them more precise than mine.

The learning objectives and the descriptions of what each grade means can be given to the student. A course may have different learning objectives, each with their own description. Your assessment can be tailored to measure the learning objectives based on these criteria.

The idea, apart from making your job of assessing more objective, is to replace scores by learning objectives, so ultimately the course will not be about scoring points, but learning.
You could even disassociate the grades from the learning objectives and replace them by unsatisfactory, satisfactory, good, very good, excellent, and fantabulous.