Be sure to
read the book until the end and close it with one click which counts as it being read, not with double-click which counts as aborting reading it and doesn't bring any experience. Best for such training of intelligence is a very short book with only one page, which you can open again and again, and finish also immediately with a single click. But you should be able to find enough books in the library of Tenebrae in the east part of the town (going through the gates at the right side from the palace).
As for practicing strength and dexterity, if it gets tedious after a while to whack with the weapon at the air, you can also climb up the walls and jump down again, or simply jump around which also trains both.
If you want to see what the consequences are for stealing stuff in the town and being caught, save the game and do so where you can be seen. It's pretty funny
