Hi
Have you tried mapping? For Pick the Middle questions in particular, that's a great way of trying to see the pattern.
I suggest that first you identify all the individual elements present in each image.
For Pick The Middle, map one of the elements and try to find a simple pattern, such as the element moving one position clockwise every time.
For Next in the Sequence, use your finger to follow an element and see how it changes, it might move positions are certain number of times each move, or change colour/orientation every move.
Some times for Next in The Sequence I look at the first two images only and see how each element has changed. I do this again for the second and the third image and see if the changes are consistent.
As to getting better at these questions, you just need to be able to identify patterns and practice doing so in order to answer the questions more easily. Medentry should have a guide on common patterns. Daniel Mills on Youtube also has a good section 3 tutorial if you want to be able to identify patterns more easily.
Hope this helps. All the best