Often you won't present yourself as an SE. Sometimes it is easier to get access to a customer posing under various other guises.
SEs can fill a number of roles in an organisation, the title of Sales Engineer is really an internal job description or designation of the focus of your work with customers. The focus of the role is to be the technical face of the solution or product offering in dealings with prospects and customers.
It can be a 'guerilla' style tactic to turn up on customer sites more often than you might if you wait for the Account Manager to get you there.
Suppose your company has some consulting work or perhaps a support visit with the customer, but there is also an opportunity to sell more software or services in the account, then ideally an SE can go along as the Consultant or Support Engineer to perform the activity, potentially accompanying other staff. It this situation, you can find out more information than the customer might give during a sales pitch kind of meeting. You might find out who really runs the project, or some new business objective that needs to be solved. All of a sudden you might get the jump on the competition and be able to alter the proposal to meet your customer's needs.
If you can't get on-site, you still might be able to get the other technical staff to find out answers to your questions while they are there.
Titles that an SE could use to perform these tasks include:
* Technical Account Manager (TAM)
* Field Engineer
* Technical Consultant
* Solution Engineer (Also abbreviates to SE)
* Project Manager
* Technical Manager
* Solution Specialist
* Solution Architect
* Enterprise Architect
* Systems Engineer
While some of these titles don't sound that flash, it can be important for the 'disguise' aspect of the SE job to go in with these titles as a good reason to visit the customer and to be a trusted opinion.