Whatever kind of test you're doing, there's one thing you should always do!
Whether you're a child doing a grammar school entrance test, a teenager preparing for science GCSEs or an adult taking a driving test theory paper there's one thing in common which you should do to be prepared. Practice with past papers or tests.
Although around a 20% of children are tutored for grammar school entrance, you'd be surprised how many parents avoid letting their child take a mock grammar school test paper in case they 'over achieve' and then struggle in grammar school. It is an understandable sentiment but the Sutton Trust, who focus on social mobility and education, recognise that all students would benefit from ten hours of tuition to help familiarise them with the test. Much of this tuition would focus on past papers so that children are aware of what to expect in the test.
At GCSE and A level, there is now a wealth of past papers available online. Many of these come with marking schemes and examiners' reports to indicate how students can answer questions to get the best marks and to identify common errors. Clearly other forms of revision are important, but using past papers is a good way of identifying topics that are likely to be included in examinations and the kind of wording used.
Mercifully, many of us are spared regular tests and examinations in adulthood, but on occasion we may need to take a test, such as the driving theory test. Many online examples of the tests are available and these can really help you prepare, by knowing the kind of tasks you'll have to tackle on the day.
With so many resources available on the internet, there is little excuse for not having at the very least a quick look at previous examples of tests, whether you're at primary school or a more mature adult who's a bit rusty at taking exams!