The aptitude tests are pre easy so dw about them - in regards to big4 and below calibre firms. If you have 65+ wam, you can get into any of the big4 service lines with ease except deals/transactions where there are little spots available. The interview process for all b4 is easy. The basic behavioural questions you can find online. Only tip is to fully understand the service line you are applying for if you are applying for the more difficult ones.
But if you are going for MBB or tier 2 consulting, you should start case practice soon. If you're going for IB, make sure you understand basic corporate finance principles - for the interview stages. But if you don't have 75+ wam, some ECs or comp experience in the first place, don't bother wasting your time applying for these guys because there is 0% chance you'll get through (unless you know someone and they vouch for you of course).
Final tip is that networking actually works and is not a myth (Especially to get into the tougher roles) - but it's not necessary