Here's five useful things we've learned about the humble micro:bit..
1. The JST battery socket should not be used with rechargeable lithium-polymer batteries - this is because the connector is only build for 3.6V. Lithium-polymer batteries that supply between 3.7-4.2V can overload your micro:bit's circuitry. So stick to battery packs with alkaline batteries, like those that come with the go/essentials kits.
2. The micro:bit will always select the highest power source. What this means is that when you plug in the microUSB lead, which is around 5V, this is always going to be used, even when a battery is connected to the JST socket. So you don't have to worry about disconnecting the battery pack when plugging in the microUSB lead to your computer.
3. It's good to use a protective case with your micro:bit where possible, and pick it up carefully by the edges. Metal surfaces (like that macbook you may be tempted to place your micro:bit on), or liquids such as excessive oil/perspiration from your fingers, can potentially short-circuit and damage your micro:bit. There's lots of information, including how to look after your micro:bit, on the micro:bit website here. This is the same information that you may have received in a leaflet with your micro:bit.
4. Your micro:bit has a maintenance mode, which allows you to upgrade its firmware. Access this mode by holding down the reset button, while connecting the microUSB cable, without a battery attached. If you see 'maintenance' on your computer when you plug your micro:bit in, you may have accidentally held down the reset switch when connecting it - if you're not updating the firmware, just disconnect it and reconnect it. New firmware may be required if you want to use a new feature and the process for upgrading can be found on the official micro:bit site here.
5. Sometimes it's not possible to fit all the required libraries onto your micro:bit; for example, some MakeCode packages may not be able to coexist with other functionality, such as bluetooth. It's important to test out your ideas in stages, to ensure that the combination of functionality you require, can run alongside other required functionality - however, if you think outside the box, you may be able to offload functionality to another micro:bit, if you can send the data wirelessly.