Hi Ash
Can’t say our methods are in any way perfect, I think it depends on their mood at any given time; but we found using timeouts for bad behaviour, and a sticker chart with specific ‘good behaviour’s’ (for example tidying up toys or behaving on a trip to the shops) helped with keeping discipline. we give a set target of stickers per day/week which if hit my son gets rewarded with a special treat, which was normally a toy car or something like that (nothing expensive, but specifically related to whatever his main interest is at the time) and made the chart a focal point throughout the day.
It may not always work but if you are looking for ideas it may be worth a try, good luck with whatever method you choose, I’m sure there are many out there that will help!