Congratulations! You have already got further than many people by deciding to go ahead with your presentation despite your natural fears. When starting to prepare for your presentation, think about the:
1. Environment - where will the presentation take place? Does the size and layout of the room suit your purposes? Is it to be formal of informal? Are all the necessary facilities available?
What kind of aids do you need? Would some props would be useful? If using technology, always have a back-up so that a technical failure does not bring everything to a halt.
How much time have you got? 30 minutes sounds a long time, but can go very quickly, particularly if people are asking questions.
2. Audience - who are they? How many will there be and what do they already know? Should your language be technical or colloquial? What kind of questions might they ask? Are they friendly or do they need convincing?
3. Objective - what are you trying to achieve here? Using that reliable old technique, the SMART objective, will help you here. In other words your objective should be Specific, Measurable, Achievable, Realistic/Relevant and Timebound.
4. Structure - you need to have a clear structure so that people will follow what you are saying. My favourite is the 5-part structure of:
Attention-grabber - an interesting anecdote or maybe some unexpected fact or statistic.
Introduction - tell them what you are going to tell them and why!
Main body - see Content below.
Conclusion - sum up your arguments neatly.
Link back to the attention-grabber to close.
5. Content - keep it short and simple. It is tempting to stick in lots of detail to show how knowledgeable you are, but you may only succeed in sending the audience to sleep. Never pretend to know more than you do. It is very embarrassing to get caught out!
Having got this far, you now need to practise your presentation, preferably with a sympathetic but objective observer to give you feedback. Only by talking out loud will you become comfortable with your material and discover what flows well when spoken, as opposed to what reads well on the page. You may need to make adjustments to avoid stumbling over words or to clarify their meaning. Keep practising until you feel completely comfortable with the content - this is one time when trying to fly by the seat of your pants just isn't worth it!