The first and most important thing that you need to do in order to increase your productivity at work is to make a list of tasks that you are expected to do at work. Do not miss out anything. Once you have thought up of all the tasks, order them on basis of their priority. Use your knowledge and personal judgment to decide which tasks should be completed earliest and which can be safely done later.
Once you have listed the tasks and assigned them priorities, map them out in such a way that you get to start with the high-priority tasks first and then move on to the tasks with less priority. You can think of it as a schedule that you will be following on daily basis.
Do not allow yourself to get distracted while you are at work. It is very easy to succumb to the temptation of frequently checking email or logging on to Facebook to see what the rest of the social network is up to. However, learn to control these urges and stay focused on your office work. There will be plenty of time for you to spend on interacting with your social network after work.
At about lunch time, look at the priority to-do list that you made in the first and second step to determine whether you are on schedule, trailing behind or are actually managing to stay ahead. If you are trailing behind, consider shortening your lunch break and getting back to work earlier. If you are ahead of the schedule, you are doing pretty well. Being on schedule is not too bad either.
Do not end up asking for responsibility that you can't handle just to make a good impression on your employer. While extra work is sure to get you noticed, do not overdo it, as failing to complete the new task will get you in trouble rather than getting you a pat on the back.
Make sure you have a clean and organised work-station. You will find it easier to find your things such as pen, paper, etc. and thus save valuable time, which you can use to do an extra bit of work.