What can I do to improve my presentation skills?

If Presentation is a Skill, then it has to be learnt through PRACTICE. Practice, practice and practice is my first advice.
You have no problems. These are fears. Perhaps on one or two occasions the 'Murphy Monkey' jumped on to your back as soon as you started your presentation. The next time throw him off. Be confident. Tell yourself that you can do it.
Practice in front of a large looking glass.
Carry some Note Cards with you.
Write the beginning, the Main Points and the ending.
Use a Power Point Show with notes for you.
Build up your confidence.
Watch some good presenters on allied themes and topics.
Observe their body language, their voice modulations and also Read some Books on Presentation Skills.
Search for Video Clips on Presentation Skills. Some good ones are available on the YouTube also.