Be fair, and kind. These are the two biggest factors in winning over your class, based on what the children say. If someone needs help, give it. If it is not a good time, or you are busy elsewhere then explain that you will get there shortly. If a child is making bad choices then don't ignore it if you reprimanded another child for the same reason a moment ago. Give out responsibilities evenly. Key words here are patient, friendly, firm, kind and consistent.
Play games. Quick games like the 'Yes No game' or 'Greedy Pigs' take only a few moments, but really engage all but the most disinterested children. Do lots of little games to fill in empty moments at the beginning of a lesson, or waiting to get the call for assembly etc.
Do brain-breaks. These are little activities designed to stimulate the children's brains and help them focus. They are also quite good fun, and will capture the children's attention.
Keep the pace up - especially if following your own plans. Don't spend too much time talking, get the class doing and active as much as possible. Use your intuition, if a class is getting restless figure out why. Is it because they are bored by the activity - is it too easy? Too hard? Change it, alter the focus slightly. Take the learning forward by doing a different activity which involves a different related skill.
Tips: during the teacher input, get he children involved as much as possible. Have them demonstrating, choosing volunteers on your behalf, looking for 'good listeners' etc. When looking for a child to respond, don't ask for hands up, use a 'finger of fate' - close your eyes and wave your finger around the room. Ask for a shout of 'stop'. Open your eyes and stop your finger. Use your discretion and choose a likely candidate from the direction you are pointing - again this is involving and seems 'fair'.
Learn names as quickly as you can. I have a terrible memory for names, so I try to get the key characters names ingrained quickly (so I can be specific with praise). For the rest, I usually say 'Miss' or 'Sir' until I can remember. Children like this because it empowers them with some respect from you.
Although it is counter-intuitive, I have found that a period of 'silence' is often welcomed. If the noise levels in the class are reaching cacophony levels, stop the class and explain that that you can see some brilliant learning going on. Explain that they are not being punished, but 5 minutes of silence will really help get their minds focussed. Ask for an extra 'push' for 5 minutes only. Usually you will find that after some subtle enforcement, the silence period will continue for quite some time...
Behaviour Policy Note
Your school will have a behaviour policy. If the children are used to this policy, you must not deviate from it. However, your expectations should be appropriately adjusted. The class will be unsettled, and they will try your boundaries. My advice is to give them a short period of grace. Explain that poor choices will receive reprimands, but that you would much rather give out stickers and praise for good choices. There may be some children for which this approach simply isn't working. Use the behaviour policy, but take care to administer it fairly and consistently. Signal what is about to happen if behaviour doesn't change, and what you expect the child in question to do about it. Give the child enough time to adjust their behaviour, but do not show weakness if the child continues to try your resolve. Escalate the behaviour to 'time out' or even to 'internal exclusion' - but do this as a last resort. Remember, be positive, fair and proactive and you will rarely experience this. Tip: Humour can often diffuse a situation - just make sure you don't do it at a child's expense - self depreciating jokes work much better.