[itexuk]

Bit late in the day, but go and have a look from the outside and if a shop the inside to see where you might be working, what they sell, prices etc. If it is a chain of dealers see if any info on the Internet re their business etc, this will give you a feel for the business.
Go neat and tidy
Do NOT have a drink before interview ( they will smell it)
If you smoke do not go in stinking of fag smoke, and don't smoke even if they offer you one.
Ask about training internal and external.
Salary, Holiday pay, Bonus schemes, overtime.
Take a CV with you in envelope not srewed up in your pocket
Take a list of question you would like to ask them about their business.
These could include but only ask questions that you understand yourself.
What's their strategy to improve sales, margins, customers
Aims and objectives re customer satisfaction
Advertising, promotions.

Good luck.