When does a museum visit start? Some people might say, "after I pay my admission and enter the exhibit galleries."
However, there are two initial points of contact that come earlier for most visitors: your museum website and your admissions area.
Put yourself in your visitor's shoes and consider what are the simplest ways to complete the desired informational transactions? Are you making pretty nested webpages and slick (but slow-loading) Flash animations that are impossible to click past when most visitors just want hours, admissions, and directions?
Similarly, do your admissions prices, levels, and options make for quick and simple transactions, or just frustrate and annoy visitors, especially first-time visitors?
The American Museum of Natural History in New York City is the all-time champ for confusing admissions prices and options, not to mention a crazily ineffective computer-based admissions system. For example, half of the computer terminals at one of their admissions areas are only for non-member transactions. So even if everyone in line is a member, three admissions personnel (on average) just stare into space or repeatedly tell annoyed members that "this computer is only for non-members."
Also, members are supposed to receive free admission to special exhibitions --- except when the museum makes exceptions and charges extra for special exhibitions. Does this make for great customer satisfaction? Not in my case! After repeatedly running the AMNH admissions gantlet, I gave up and canceled my family membership!
So think about the "visit" that starts before your visitors start enjoying the first of your exhibit spaces.