Sounds like you probably mean "introvert" when you say "smart" in this post. They are kind of two different things, though there is often a correlation due to a tendency to appreciate books, and other autodidactic benefits.
Speaking as an introvert myself, one of the main challenges is to find ways to turn off the self-consciousness in some circumstances. For instance when giving a presentation or performance in front of an audience is no time to be shy.
Another challenge is finding avenues to interact with people that can allow you to gauge mutual attraction fairly early and painlessly.
It is possible to be extroverted and smart and introverted and dumb as a stump. Saying "smart" is a safe description because it implies that a person thinks well not necessarily educated well. It isn't necessarily wisdom because that is a function of experience. It isn't necessarily a function of intelligence because there are lots of intelligent people (high IQ) who are neither wise nor smart (see dumb as a stump).
Yes , introvert is more correctly. I am introvert too. I understand what you talking about :)