Owning a car in Boston takes some getting used to. In some neighborhoods you will need to get a "resident parking permit" to park on the street. It's free and you get them from city hall, but it does require some paperwork. Once you have one you just need to be mindful of the days on which the City sends sweepers through to clean the streets.
When it snows, you'll obviously have to dig the car out. It takes some time and energy, but when you look at how much time having a car saves you, it may feel like it's worth it to you.
Having a parking space of your very own would be ideal. Whether you are renting an apartment or buying a home, some will have parking spaces that go with them, but most will not. There is a secondary market you can access where people rent parking spaces. Rental parking rates are going to differ dramatically depending on what part of town you happen to reside in.
If you are only going to need a car occasionally, you may want to join with Zipcar and rent a car by the hour. A lot of the hassles and expenses that come with owning your own car will go away, but you still get to have the convenience when you need it.
Hopefully that covers it. If you still want to know more, you can reach me through Trulia.
Certain neighborhoods are very difficult, such as the North and West Ends.
Back Bay and South End offer a lot of residential parking (with sticker), but street cleaning from April-Jan can create a headache.
Parking spaces range from around $150-$450p/month as a rental, depending on neighborhood.
If you reverse commute (leave city during day), then parking can be around $150.
The MBTA is a very convenient solution for most of Boston, so that makes things easier.