What steps should I go through to pick an interior designer?
Choosing a designer is tough and can be a lot like throwing a dart at a dart board. You have to find someone who understands your sense of style and whom you also get along with.
For starters, you need to decide whether you are paying the designer to create a look or just to execute the project under your direction. Review a designer's portfolio and see if you are on the same page in terms of budget and what they can deliver. A good designer can work within any budget while keeping the style unique.
Beware of designers who crank out the same look for each project. I admit that I am biased, but hiring someone trained in both architecture and interior design gives you the best of two worlds and (hopefully) a cohesive project. But no matter what, do your homework before hiring anyone.