Is this a new client?  One thing to look at is how organized they are.

If they come in and hand you a W-10 for daycare, a printout of the financial account from the college, an itemized list of expenses for each separate rental along with an accurate depreciation schedule, a log of hours performed and vehicle mileage for the rentals, the purchase and selling paperwork of the sold rental and an explanation of why they withdrew their retirement early, it could be a fairly easy return.

On the flip side, if you need to inform them of a huge list of things that you need, repeatedly ask them a million questions, figure out prior depreciation, correct prior depreciation with Form 3115, etc., it could be a very time consuming and expensive tax return.