How should a one year experienced software engineer prepare for a job interview?

If you have been working in a product company which follows necessary standards like proper source control, automated deployment, automated testing for every step, documentation, I am sure you should not have any problem cracking the interview

Experienced developers are treated differently than freshers, although the years of experience would be less. Let me note down few topics which would be helpful to be known before going for an technical interview
Databases

  1. Understanding ER Diagram of a given system. Being able to convert an scenario into database schema and the level of normalization.
  2. The main difference between all times of join from inner join to full outer join(trust me even many experience do not know joins properly)
  3. Different type of Indexing , Caching, avoiding (n+1) query scenario and optimising queries for better performance.
  4. Database scaling strategies like vertical sharding, horizontal sharding, master-slave.

ServerSide
Server-Side Programming can be any language but should be familiar with architectures like MVC,SOA. One should be familar with the entire request-response cycle, which helps to develop any part of the application. Specialization in the Server side technology that you have been working.

Data Structure and Algorithms
Many Experienced tend to forget the basics of Data Structures and Algorithms. The Basic Concepts of Data Structure, being able to develop the most optimised data structure for a particular case, algorithms strategies like greedy,dynamic,etc should be known.
Searching and Sorting techniques with its time Complexity and one should be able implement them in any one language.(I have seen experienced developers arguing about sorting techniques). This may tend to go back to the textbooks but you should not hesitate for that.

If you have been working in a product company which follows necessary standards like proper source control, automated deployment, automated testing for every step, documentation, I am sure you should not have any problem cracking the interview

In general, be aware of the latest happening in the field you are working on. Be ready to explore and experiment. Be well read and aware by following good people on twitter, reading good articles, being active on mailing lists, answering/asking questions on stackoverflow, Having some open source contribution(Even small pull request for typos looks good), Meeting people on meetups and conferences.