Online: Websites such as indeed.com, monster.com, job postings on LinkedIn, etc. provide easy access to several available jobs. You can also search for positions on Nittany Lion Careers, which is a university-wide career services management system for all Penn State students. You should be able to find information on internships and full-time positions here. Most applicants use this method because of its convenience and therefore it would be best to also use other strategies.
Career fairs: Career fairs at Penn State can be another great way to learn about different companies and the types of jobs available. You could refer to career fairs information on the career services website to learn about upcoming events and jobs available.
Networking can prove to be a very effective strategy to find a job because people often take seriously recommendations they get from their colleagues about potential employees. You could go about this process by reaching out to your mentors, family, and their contacts that might know of any available position in their companies. You would need to think about the types of jobs you are looking for and communicate that information to people in your network so they can connect you with the relevant people.
Although this method is very time intensive, it could sometimes be beneficial. You could go about doing this by first thinking about the types of positions you may want. You could search for individuals with similar job titles on LinkedIn and either message them from LinkedIn itself or try to search for their contact information from websites such as Email Hunter.
Turning an internship into a job
Companies often try to select interns with the goal of eventually hiring them as full time employees because they have a preview of your performance on the job. It will also gives you an opportunity to become familiar with the type of work you would do and the company or work group culture. Therefore, you could also look out for an internship in an area of interest towards the end of your graduate school career as this could potentially turn into a full time position upon graduation.