how to prepare for AIBE

Read bare acts as per syllabus.

be thorough CPC and Cr.PC.

There are five types of questions which usually appear in AIBE:
1. Sections,
2. Judgements (case laws),
3. Historical,
4. Analytical, and
5. Maxims.
You will be allowed to carry bare acts without notes or comments to the examination hall, so no need to memorise sections, or dates.
But you do need to remember important case laws, landmark judgements, and legal maxims.
Search for previous years' question papers and try answering them using only the requisite bare acts, and time yourself.
AIBE is a fairly easy exam, considering everything.
Hope this helps.