The singular "their" is often preferred if you have no other choice. There are several other options:
Use the second person:
If as a student, you have a process, you can improve it from your own experience or other's feedback.
Use the imperative form:
When a student has a process, improve it from experience or other's feedback.
Use the passive voice:
A student's process can be improved from student experience or other feedback.
Reuse the noun:
When a student has a process, it can be improved from the student's experience or other feedback.
Use the plural:
When students develop processes, they can improve them from their experience or other feedback.
If you can it's best to rewrite the sentence to entirely avoid the need for a gendered pronoun. There is a bit of an "art" to this that improves with practice:
Student-developed processes can be improved through experience or feedback.
"His/her" is not usually recommended, and using the female singular "her" can be distracting and seem "politically correct". Plus, it's still not "gender-neutral".
Finally (and despite the possible views of school administrations) it's not appropriate to refer to students as objects by using "it", even if you don't like them. :)