As you embark on your search, one thing that applicants must get right when looking for intern jobs is their resume and cover letter. At their best, these documents are expected to 'speak' in your absence. Therefore, it is important for you to take appropriate time to give them your very best shot. Do not be in a hurry to start sending out your applications. Rather, it is better that you take time to prepare something that will give you little reason to regret once you begin to send it out. Resume and cover letter writing is a skill and you cannot afford to take an 'anything goes' approach here if you hope to get interview invites for internship jobs.
When drafting your resume, first thing you must identify is the type of companies you would like to approach. This is important since your resume and cover letter must be structured in a way that is relevant for that particular organization. That said you must be flexible enough to amend your resume as you send it to different organizations. For example, you could be targeting internship jobs in accounting but in two different organizations: one in advertising and the other in the oil industry. Your resumes may need to be tailored to meet the requirements that one would expect from these two different organizations even though theoretically the position sought in the two organizations is the same. One must never lose sight of the overall long-term goal of securing an internship.
As you apply for the internship jobs, one of the things you want to do using the cover letter is to establish a connection with the company. It is important that you demonstrate an interest in what the company's core business is. Once you do that, you can now move on to briefly talk about your experience and education and how these would tie into not just the internship jobs you would be interested in doing but also the overall strategic objective of the target company. Highlight key achievements you have made even outside the sphere of employment but that aptly demonstrates your ability to deliver on the job. As you do this, guard against exaggeration. Aim to bring out the best of your abilities but make sure that the achievements you list are factual and can stand if subjected to the independent reference of a third party.
Finally, end the cover letter well by confidently but not abrasively showing why you would be the best person for the position over any other applicants and why you would want to work with that particular organization as opposed to any other that may be in a similar industry. Doing this should give you an edge and increase your chances of success.