Click on the link above to have a look at local recruitment agency Concept Personnel's blog on "How to make your internship a success". This is a very helpful piece for whether you are applying for a placement, internship or even starting a new job. The top 3 tips I think from this blog are:
Show Enthusiasm - You should look like this is a job that you're interested in and want to learn about.
Be Proactive - Show that you are keen to do as much work as possible, don't sit around and play on the internet when you've finished your task. Ask for feedback or if there is another task you can start.
Ask Questions - Try to learn as much as possible while you are there, it will help you understand how businesses work and will help you in future jobs. Also ask about the work you are doing and for feedback, you won't improve if you don't.