Kiswahili is a typical trade language; you will find a mixture of Arab, Bantu and English words in it. The pronunciation is phonetic, that makes it easier to speak. Many words have just been taken from another language and have been given a Swahili sound to it. For example Dereva meaning Driver, Gari meaning Car, Manispa meaning Municipal etc. There are not so many irregularities in the language but if anybody tells you that Kiswahili is an easy language DO NOT BELIEVE IT!! There are many ways to say the same thing and a word can have many meanings.
If you want to study Swahili you can do it on Zanzibar at the Taasisi School for Languages, the official name is SUZA, but here everybody still calls it Taasisi. You can hire a private teacher or you can do a course.
A good website to help you is the SurfaceLanguages with a dictionary and a learning guide.
If you just want to be able to communicate a little bit, then these following words may help you.
Greetings in Africa are very important and should not be rushed. The tourist way to greet is Jambo but it is not good Swahili.
Hujambo answer Sijambo (it means do you have any problems and the answer is I don't have any problems). To more people the question is Hamjambo and the answer should be Hatujambo.
How is your morning/afternoon/evening? Habari za Asubuhi/Jioni/Usiku How is your day? Habari za Leo
How is your trip? Habari ya safari?
How is at home? Habari ya nyumbani?
And so on and so on (family, land, health, children, business, work etc.)
Habari means what is the news of.. and the answer is "Nzuri" (good). If things are particularly good, then the answer might be "Nzuri sana" (very good).
So remember: Habari za.... Nzuri!
The formal greeting is Shikamoo to one person and the answer should be Marahaba. It is very impolite not to answer a Shikamoo. To a group you will say Shikamoni, the answer is Marahaba.
The "Cool" way of greeting is also very important:
Mambo? / Mambo vipi? Means Hey, what's up!
You can answer in three different ways: 1. Poa! (cool) 2. Freshi! (fresh) 3. Bomba! (fantastic)