Here are some general guidelines from Toastmasters (a non-profit organization for helping people improve their public speaking).

I. Guidelines for Speakers:

1. Be able to take criticism. Do not take criticisms personal, just learn from them and move on.
2. Realize that the physiological condition of nervousness that occurs when getting in front of a group, is the same as for excitement (think about it - sweaty palms, fast talking, etc.) That means you can use your nervousness to convey a sense of enthusiasm - in other words, do not worry about getting rid of your butterfiles, instead, work on getting your butterflies to fly in formation!
3. Try to talk slowly (obviously not too slowly). When nervous we have a tendency to talk fast and it can be very ineffective. Trust me, what might seem to be very slow speech to you while up in front of a crowd, will sound very controlled to the audience. Practicing in front of others will help.
4. Try to avoid distracting postures. e.g. The guy from Motorola would often put his hand to his mouth which kind of distracts the audience from the presentation. Other examples:
o The fig leaf - clasping your hands together in front of you/behind you.
o Scrathing your head, rubbing your eyes, picking your nose :)
o leaning on the lecturn or nerby tables etc. This is less of a problem depending on the formality of your speach but can be distracting.
5. Dress appropriately - don't wear distracting clothing and dress appropriately for the talk. e.g. if your presentation is very informal you do not have to wear a suit - always take corporate culture into account on this one. Texas Instruments, where I work, is a very casual environment where wearing a suit can be distracting. I've been to (TI internal) state-of-the-union meetings where our VP gave his presentation in jeans and a polo shirt.
6. Of course there are the obvous things about knowing your audience, speak loudly and clearly, etc.
7. When using overheads ALWAYS check after you put a new on the projector. You never know when one is upside down, crooked, flipped over, etc. So always check.
8. Time your speeches. Plan on having a fixed time and practise until you hit that time. This is crucial because you may only have a fixed time to give a speech, so you need to learn how to do it. In Toastmasters a person volunteers as the timer and will flag the speaker when they are half through, when they have five minutes left, and when they have 90 seconds to go. All of you speeches in this class are to be 15 minutes long.
9. Work on using good phrases. Do not spend five minutes poorly explaining something that a few good sentences (and maybe an appropriate overhead) can illuminate. Be as precise as possible without losing your audience. The more you understand your material the easier this is.
10. Avoid ever saying "um", "uh", or "ah". These filler words are useless and distracting. I was channel surfing once and came across a Senator on C-Span who actually said an English word every three or four "ah"'s. He was impossible to listen to. Besides being distracting these words might also convey a sense of insecurity. People who talk with authority don't say "um" very much. In Toastmasters someone volunteers to be the "buzzer". They have a small device that puts out a load obnoxious buzz whenever a speaker "um"s. This breaks the habit in a hurry!!!
11. Avoid excessive use of conjunctions (and, or, etc.). Some people will try to chain every sentence of their speech together using "and". All these "and`s" can be distracting.
12. Use proper English grammar (this is highly related to 9 through 11).

II. Guidelines for Evaluators:

Evaluation is a crucial part of a Toastmasters meeting. Obviously without good feedback you do not know what needs improving. In a meeting there is one evaluater for each prepared speech, and then a general evaluator who evaluates everyone who spoke. You might want to designate someone to be your evaluator. The reason is that it is nearly impossible to really pay attention to minute details of the presenters style and really listen to the content of the speech. If you really want a good evaluation, pick someone who will really focus on your style according to the criteria above. When you get more acquainted with the criteria, it is easier to focus on the content of the speach and grammar. But most people struggle with their presentation style the most, so focus your evaluations accordingly.

Below are some guidlines for effective evaluation.

1. Always give praise. There is always something you can say a speaker did pretty well, so say so. An important part of receiving an evaluation is to learn what you did well, not just what needs improvement.
2. Realize that constructive criticism is not "you did ... really terrible!" A constructive criticsm is "You said 'um' a lot during your speech. Instead, try to just pause between thoughts". If you can't think of a general solution to their problem, try to think of a specific example of how the speaker might have done better.
3. Learn from the evaluations you give to others!