The first step is to read the eligibility requirements carefully. They are all as different as the externships for which you are applying. Some areas to watch out for are college level, skills, experience and any special requirements such as bi-lingual skills. You may be an excellent candidate, but if you don't meet the requirements, don't apply. Many law externships, for example, only apply to third- and fourth-year law students. In addition, don't try to fudge your way past critical skill areas. If the externship description wants students who have a working knowledge of graphic design software, you must have enough experience to hit the ground running.
Also be aware that many externships require approval from a professor. If this is the case, plan ahead by letting your professor know well in advance that you are interested in an externship position.
Deadlines are very important, especially if you are applying for more than one externship. Keep a list of all the externships that interest you and note their deadlines for applying. Be sure to add a column for "Date application sent" in order to keep track of when you completed each application. This will help you track their progress. Include contact information so you can call to check on the status of your application.
Most applications can be done online. They generally include completing an online application that can be submitted, along with such documents as a cover letter, resume, college transcripts, and proof of a skill set such as writing, graphic design work, or published articles. Carefully review the requirements for your chosen placements, and include work samples if required. It is a good idea to assemble all these materials ahead of time as it will expedite the application process. This includes all the general information that is included on the application form, too.
Make sure you have these materials available in different formats, such as jpeg, PDF, Word, etc. Each externship application will have different requirements on formats. Be sure to comply with the required format or the application may be considered incomplete and rejected.
Be aware that some larger companies post dozens of available externships. In this case, students are generally given a link to register and apply on the company's career website. When searching for an externship, using the "externship" word search is required. It also enables students to search for a wide variety of externships not only in the U.S. but internationally.
Applying for externships is basically a matter of reading carefully and following directions. Making sure all your supporting materials are perfect is also important. It is a good idea to have a few people review your cover letter, resume and work samples ahead of time to ensure that they are representing your best efforts. Being prepared and paying attention to details will make the application process much more rewarding.