Well, the curve of lips has won many battles, and meetings are no different. A smile can increase your odds of creating a good impression on the people you are meeting. However, overdoing it might make you look nervous and creates an awkward situation.
Yes, the way you dress does make an impact on people. However, this does not imply that you can make a lasting impression only if you wear the latest fashion or the most expensive clothes. Your appearance should be in tandem with the setting of your meeting. For interviews and client meetings, one should stick to formals. At the same time, things like unkempt hair, untidy clothes, or loud makeup are a big no-no. You could go with casual chic or casual wear for more informal meetings like office parties.