Hi jojo,
some of these tests are regarding assessing your personality (famous Myers Briggs Type Indicator) which provides a characteristic profile of yourself. Strictly speaking there is no right or wrong personality, yet obviously certain firms problably want certain characteristics (e.g. teamworker in hospital, innovativ in design etc.) You can influence this a bit by guessing what the question may be hinting at and then answer accordingly. However risk of getting it wrong and creating a profile which dose not reflect you at all!
Regarding the strict numerical tests these usually like intelligence tests and look at logical thinking and pattern recognition. The trick is to try and find the pattern. Focussing on this may help, practise, practise, practise is the main thing. Do not think that theory here helps! Try and keep everything logical and rational!
Good luck