Look at the video before you edit, and give yourself plenty of time to think about it.
The first thing to keep in mind is that video does not edit itself. You have to look at the video and apply some creative decision-making and critical thinking to decide what to keep in the finished product, and what to cut out and “leave on the cutting room floor”. The temptation will be to include pieces of video that you love, and that’s probably when you need to revisit the editing table after walking away from a bit with a clear and detached mind.
Of utmost importance is that you block out the time necessary to look at the video. There is no substitute for this long and tedious process. You can and should take notes about the portions of the video that are worth keeping in your judgment, and jot down the begin and end times of those portions.
Then, walk away. You need to reflect, and even sleep on it. There is scientific research that suggests that sleep consolidates your memories in an organized way and is more conducive to later retrieval.
Return to the editing table (your editing software), and make “splits” at the begin and end times of those portions that you intend to keep. Scrub through the video (use your mouse to move the vertical line that positions the video in your editing monitor display), to make sure you are preserving the right portions, and delete the portions you will not use. Cut them out.
What you will have left is a very rough cut. You can smooth out these portions with transitions such as dissolves; and you can trim the length of the clips (if more than one) to a “just-right” length. When all that’s done you can go back and overlay title graphics and lower thirds (text captions near the bottom of the screen).
Review the finished cut and make any additional trims that are necessary.
Then save it out as your master and export the final product that you will need to distribute or submit as an assignment.