How do you operate?
Mortgage advisers operate over the phone and face-to-face. Both work well, so your choice will ultimately come down to personal preference. The important point is that they are easy to get hold of and that you understand their advice

What other services can you offer me?

A good adviser will recommend protection such as life cover and home insurance when you take out a mortgage, because it's important to be adequately covered. But it's not uncommon for a broker to be whole of market in terms of the mortgage providers they use, but tied to recommend one particular provider for other services. If you are not happy with this, there's no harm in shopping around for these extras yourself.

What can you offer me that a lender can't?
This question may stump some mortgage advisers, but ultimately there are distinct benefits of using a broker over going direct to the lender. These include impartial advice, access to the most suitable and competitive deals on the market, and assistance through the application process and beyond. Advisers will also often negotiate special deals which wouldn't be available direct from the lender, and your legal or valuation fees could be refunded too.