The FLAG website (which stands for Field-tested Learning Assessment Guide) is a good site for learning how to diversify your assessment methods. It helps you decide which type of assessment is most appropriate for measuring student achievement against your own learning goals. It describes various assessments such as: attitude surveys, concept maps, concept tests, interviews, performance assessments, and portfolios and how to use them. Although designed for science, math, and engineering courses, they can be adapted for other disciplines.
Rubrics are a useful way of letting students know what is expected from them on any given assignment. They are also useful for giving students useful feedback on their strengths and weaknesses, and for increasing the consistency of instructor evaluations.
The FLAG website (link above) has detailed information on scoring rubrics but here are sample rubrics constructed by me for assessing written papers and talks. The check marks can be replaced with numerical scores if preferred, or omitted altogether.
If you have too many papers and/or insufficient time to compose feedback for each student, you can use a variant of a standardized feedback rubric that I used in my large enrollment physics courses. This type of feedback is not as good as the individualized ones, but better than nothing, because it at least tells the students the elements of good writing that you will be looking for.
The UCITE library has a good book called Introduction to Rubrics by Danelle D. Stevens and Antonia J. Levi that describes the advantages of using rubrics, and is also a practical guide to creating them. There is a website associated with the book where you can download blank templates for creating your own rubrics.