The professional way to do this is to... well, leave more or less on time. Give it 1-15 extra minutes perhaps in order not to be perceived clockwatching then go. If you have a task that is about to get finished in these 1-15 minutes, do it, otherwise shift it for tomorrow.
It's important to demonstrate from the beginning that you don't intend to let yourself be ridden on.
If you wish to demonstrate your engagement, putting in extra hours is the worst possible way to do it. First it will damage your health. Second nobody will appreciates it but instead expect this from you by default.
Be motivated during the day, the rest of the time is not paid anyway.
If you get frown at for not willing to work 10-12 hours, switch the job before it sucks you out.
UPDATE: To answer directly your question about how it is perceived, it depends. It depends on a particular company, its size and culture, it depends on the industry and finally it depends on the country and its culture. In western countries it may be generally considered wrong to work over standard hours. In eastern countries people might not even be familiar with the idea that they are entitled to personal life. Not knowing where you are, it is difficult to advice, but speaking of advanced countries and good companies, it is generally bad not only to force you to put extra hours, but even not to notice that you're doing it and damaging your health and social life. I would give you a general advice to limit your hours and remove yourself from the places that dictate to do otherwise (unless you are generously paid for doing that and you personally accept that).
A true story. At my last place of work I did put in extra hours from the beginning. As it turned out, it was quite stupid of me. Do you think anybody thanked me for that? Hold tight. I got yelled at for possibly not putting in even standard hours! You know why? Because when I was the last one to go, people were leaving without paying me a visit to say goodbye and then obviously the next day nobody remembered when I left and even when and whether they saw me at work. How's that for gratitude. Since then I started to count 8 hours then go. Did me good.
UPDATE 2: All of the above refers to product companies, that is places where you sit in an office and do your work. If you were to join a service company (consultancy), they'd send you across the country and farther to visit their clients. In that case I presume the question of working hours fades away, since if you're stuck this week in some new town, you can't do much with your personal life - your family, your friends, favorite places to visit and favorite things to do are all back home, all you can do is to wander through the town or sit in the hotel. In that case they practically owe you 24 hours, so I suppose you might as well put in more hours as just another way of spending time while not in a position to do what you'd normally do during your off hours.