If I am hard on myself then I would say that I could be more organised. The 'clever' teachers talk about working memory and my experience and own conclusion lead me to agree with the idea you can only remember so much at once, at least it seems to hold true for me. So I have to have routines to help me and if I get out of those I begin to struggle.
As a science teacher I 'have' to hand in my practical requests on Thursday for the following week. This is particularly true for me as our physics technician doesn't work on a Friday. So I need time on Wednesday or Thursday to write my lesson requests. I can change my mind, but it needs to be with appropriate notice depending on the practical lesson. I imagine other science teachers recognise this.
When I started teaching this was a bit of a struggle, especially when I wasn't as familiar as I am now with the structure of the curriculum. Within a year I had developed so that I thought ahead to the next six lessons or so to look at what we were doing. This has always been important to me to help with organisation of myself for practical work.
A good scheme of work really helps when it comes to ordering practical work. It helps to know that the practical being completed is well matched to the learning objectives and that the equipment list in the documentation is complete and detailed. Not having a stirring rod, forgetting to order the batteries, or not being given enough stop watches can cause a problem in real activities. It helps to know that on Thursday I can write an equipment list without having to deeply plan my lesson as might not know exactly the form it will take (for a variety of reasons) at that point.
I don't always go to the scheme of work, as Keith Gibbs' book has really helped me as a physics teacher, as well as the practical biology/chemistry/physics sites that are hosted by Nuffield which are excellent resources.
A technician who understand what you are trying to do is invaluable to doing good quality practical work in lessons. Anyone who has tried to complete an electricity practical where the majority of the leads don't work or orders sodium hydrogen carbonate and forgets to ask for spatulas is always grateful when the technician adds them to the order anyway or checks the leads before hand. A technician who understands and cares about what happens with the equipment once it leaves the prep room is worth their weight in gold.
The last aspect of the preparation for a practical lesson that is key, is the availability of equipment itself. In the past there have been experiments that I have not been able to do because of a missing piece of equipment. A broken oscilloscope or van der Graaf, a ripple tank with most of the accessories missing, or insufficient leads, batteries, bulbs, stopwatches so the class can't do the experiment. Lessons can quickly descend into chaos with enough working equipment. In the most recent ofsted report group working in science was pointed out as having the potential to allow students to sit back. It is a reality sometimes to work in groups of four, but it is far from ideal. (Working individually also has it's limits when H&S related to space is considered).
I am extremely fortunate to work in a department where the previous head of physics has ensured that we have an wide and varied range of equipment. When I ask the technician 'do we have...?' only once we have not. Sometimes we even have two! Part of this circumstance is due to the attitude of our students, they return the items at the end of the lesson and very rarely is a stop watch or thermometer lost.
Organising practical work is an added dimension to behaviour management for science teachers. There are a few aspects to this. Getting instructions across is probably the second most important factor in ensuring that practical work is valuable to learning. (First being getting the equipment in the first place, without this the rest is irrelevant). To do this well it would be great if teachers had the time to practice all experiments, but that isn't easy. I have said this a lot, but I am finding a video of the demonstration is far more effective than a worksheet with instructions. But it takes time and confidence to prepare.
Deciding how to arrange the room is also a big factor. Again a technician can help with this. Will all the equipment be on a trolley, spread around the room, already sorted into a tray per group? And deciding what students should do when they return equipment is another. I don't find it too much at my current school, but whole experiments left in sinks was a major feature on my first school. (More time for off task behaviour while miss clears up). Often stopping the class towards the end of the practical to give this set of instructions can be more difficult than setting them off. Unsupportive technicians criticising teachers for returning 'messy trollies' also doesn't help. Unfortunately we all have to learn, including teachers learning how to manage practical lessons, putting off inexperienced teachers because the dirty and clean glassware got mixed up does not create the right climate for practical work.
The teacher has to have the subject knowledge to understand the practical work. When an electrical circuit does work, when the trace doesn't appear on the oscilloscope first time, quickly being able to predict the end point of a titration (when you know both concentrations yourself), understanding that shaking alcohol thermometers is a bad idea, realising when a round bottomed flask is more appropriate to a flat one. Those are simple examples. Why does one group get a curved graph, yet another a straight line? Why might a group find a silver beaker cools quicker than a black one?
Without understanding the purpose and science behind the experiment or demonstration yourself it is difficult enough to explain it, but also trying to concentrate on the young people in the room makes it doubly so.
So with a well stocked prep room, a supportive and knowledgable technician team, a good scheme of work, time to practice unfamiliar experiments, strong subject knowledge and strong pedagogical knowledge good quality practical work where students learn and make progress is possible.