It sounds like you may be asking about in person or online voting, so I will provide some info in both areas.
I would read the research from past conferences such as USNIX EVT/WOTE. DefCon had a voting village, this may be another source for research. People often present on voting security at different IEEE conferences as well.
You need to think about not only the software and systems, but also policies and procedures. For example, if the system is secure but there is no process to ensure all votes are collected from offline machines there could be fraud.
From a holistic perspective, you also need to make people trust the system or they may opt-out. If there is a lot of negative publicity that may reduce turnout.
With a physical digital voting system you would also want some type of physical tally print out, punch out that would ensure the total number of votes match those entered in the machine and observed by the observer.
Anonymity is difficult in any online system.
Estonia is well known for its online voting and e-Citizenry in general. You may want to review some of the things that they do and also some criticism:
- Follow My Vote: "By casting votes as transactions, we can create a blockchain which keeps track of the tallies of the votes. This way, everyone can agree on the final count because they can count the votes themselves, and because of the blockchain audit trail, they can verify that no votes were changed or removed, and no illegitimate votes were added."
- Kaspersky Polys: ccording to Kaspersky Lab, a robust voting system should ensure voter anonymity, provide protection against trash votes, vote trafficking and voter coercion, and enable voters to check that their votes have been recorded in the blockchain. It’s also important to encrypt the voting results recorded in the blockchain, otherwise intermediate results could become available before voting ends, which is often against the law.