The solution manual is invaluable here. It shows you how to perform reductions (e.g., reducing the Halting Problem to the Blank Tape Problem). It teaches you the language of "Assume we have a decider for A; construct a decider for B..."
To prove the value of the manual, let's look at a classic problem: The solution manual is invaluable here
If you find the solution manual still leaves you confused, use these alongside it: Check (requires faculty verification)
You can purchase access to the Student Solutions Manual for select editions, though for the classic Hopcroft/Ullman text, the official solutions are often bundled with the instructor’s resources. Check (requires faculty verification). though for the classic Hopcroft/Ullman text
But remember: On exam day, there is no solution manual. Just you, a pencil, and the question: "Is this language regular or context-free?"