In terms of oratory, there are three important issues - the substance of what is said, the clear order and structure of this matter, and the style and manner in which it is delivered.
have a clear open manner to the audience, and maintain general eye contact, with specific focus on key members/areas to highlight a particular point. Pacing, a clear ringing voice and making the best utilization of the cadences of words and language are all most advantageous areas to master.
Do not move about in the manner of film lawyers, nor fidget nor sway. Use the space you are in effectively. Use gestures if you can incorporate them smoothly and properly. Practice the speech/argument, and its delivery, including potential use of gestures. Use humour with caution and discretion, particularly if it is of a cliched nature, or of your own crafting.
In competition debating, rebuttal and other points will have to be made up at short notice. Use these points first before getting on with the body of your own argument. Clearly signpost the argument, so that the audience and any adjudication panel can follow the flow of your case.
In such competition debating, argument using examples is far better than rhetorical flourishes.
Under different circumstances, more in the realm of public speaking, then a different style is appropriate. Tailor your style and approach to your circumstances, the topic, and the audience. Watch footage of the great orators of the 20th century, but do not copy them verbatim; rather, pick up on relevant strategies that they employ.
It is no good given an empassioned and violently rhetorical address in the manner of the Fuhrer at the Nuremburg Rallies when you are engaged in a factual debate on rather obscure area of policy in a smallish room to a neutral audience. Rather, take his general tactic of starting slow, low and restrained, and building up into a frenzy, and apply it to your situation; start off with a measured delivery of facts, and increase the volume and intensity of your delivery somewhat towards the end, and incorporate a certain drama to your concluding remarks. Differently from the Fuhrer though, conclude quietly, wrapping up your argument with an appropriate phrase of summary or reinforcement.