For improving critical thinking, the right type of practice involves argument mapping.
Argument mapping is a way of graphically representing the logical structure of someone’s reasoning. An argument map helps you understand the evidence for and against a claim and can help decide if you should accept the claim. Argument maps work because the visual representation an argument’s logical structure makes it easier to display and investigate. For example, argument maps make it very easy to isolate individual steps in the argument for evaluation, which is one of the most crucial and difficult critical thinking skills.
An additional benefit of argument mapping is that it makes discussing arguments much easier and aids the teaching of critical thinking because your class facilitator and fellow participants can more readily see exactly what your reasoning is. This allows for the rapid and reliable feedback needed for deliberate practice. (For evidence on the effectiveness of argument mapping see the relevant section in this short paper by Tim van Gelder or this longer paper by Charles Twardy.)