My humble suggestions/experience on steps in choosing bridal studio:
1) Both of you must envision and communicate what you want/how you want your wedding to be like. Talk to married friends, flip through wedding mags and read wedding forums for ideas, valuable advices and recommendations. In short, know what you want (as a couple) and do your homework.
2) Work out a budget and try to stick to it.
3) Shortlist a few bridal studios and visit them to check-out their package. Be nice and friendly. Tell them that you heard good reviews about them from friends/online, and you're also shortlisted some other bridal studios before making the final decision. This shows that you know your stuff (to prevent kena chop) and you'll most probably get better service (and more perks hopefully). Don't get 'pressurized' or 'tempted' to sign on the spot by 'offer till today only' etc.
4) Clarify any doubts, further details, hidden costs etc and write them down on the copy of package list you got from each studio.
5) Get them to show some of their selection of gowns or even try on some if possible. Bride-to-be must be satisfied with the gowns to start with.
6) After visiting all shortlisted studios, it's time for both of you to discuss, compare and decide on the ONE studio you'll engage. Consider prices, perks, gowns, service, your comfort level or 'chemistry' with them, among other factors.
7) Negotiate for extra perks or things you want in exchange with those you don't need. But don't go overboard and demand everything to go your way. Be reasonable as people have a business to run too.
Finally most importantly, both of you must enjoyed the whole process of planning for your BIG day. I know it can be very stressful but if taken positively, you can have fun and strengthen your bond at the same time. I can say that cos this is exactly what we're experiencing now
Happy planning!