Scales, measuring jugs and timers
These are now electronic, light and inexpensive. It is so convenient to be able to weigh any container, press to zero and then weigh out your ingredients. (A warning though - the batteries sometimes give up without warning, so always have plenty to spare.)
For liquids. It is important to check that the measurements on the side are clear to read. A glass jug will show you in seconds what 3 fl oz (75 ml) looks like and – this is essential – teacups, or half teacups, are not the answer.
A measuring jug is also vital when cooking rice, as this is always measured by volume rather than by weight. So when a recipe calls for fluffy 'separate' grains of rice, a simple measuring jug will help you ban the sticky stuff for ever.
If you can guess what two minutes is, then you're a better person than me. Getting into the habit of switching a timer on will, I promise, save you from any number of kitchen disasters. Very often they are incorporated into ovens but if yours does not have one built in, they can be bought separately. Memories are fallible and a timer can save a lot of hard work from going out of the window. Timers on mobile phones are also good.