Q: How can I judge the novelty of my study?

Scientific research takes a lot of hard work, and researchers do their level best to make their work excellent. Thus, as an author, it can be difficult for you to be critical of your own work or judge its novelty objectively. The only way to get a realistic view about the novelty of your study is by comparing it with other works in the field. You need to conduct an exhaustive literature search to find out if the topic of your research has been dealt with previously and how. You should then compare the research question, methodology, and results with the other studies and objectively analyze if yours is better. 

This is a really difficult task and comes more easily with experience. A good way to begin is by reading each study and rating it on a scale of 1-10. After you have read all the other works, read your own paper once again and give it an unbiased rating. This will help you make an objective comparison. 

Regarding your second question, it is important for every researcher to keep himself updated on the new developments in the field. Once again, reading the existing and new scientific literature is the only way to stay updated. You should make reading a part of your daily activities. Subscribe to the leading journals in your field so that you receive alerts whenever a new article is published. Being a member of online researcher communities like Academia.edu, Researchgate, etc., can also help you stay abreast of new developments in the field.

Read this article to learn more about how to make reading scientific literature a habit.