There are a lot of gta vice city missions in that particular gta-game. These come in different categories - meaning not all are part of the actual storyline. Of course, there are the regular storyline-missions - but, there are also, less "serious" missions, in the strip-club, for a taxi-company, for a car-showroom, for a boatyard, for an ice-cream deliverer, a film-company and more. For the regular story-missions, you contact the people involved in the actual storyline - but there are other missions where you do that thing, as well. These include calling from a pay-phone, to go on bloody missions, to work for a biker-gang, cuban/haitian gangs and more -- being the "secondary missions".
Let's go into some of the main-missions... the first one out of these is set on a boat. It's not at all difficult to complete, and will give you a hundred bucks. The boat's populace is - of course, as this is a mafia-game - the highrollers of the town (which is exactly why doing a mission on this boat would be effective).
Next one gives twice the money that the first one gave, and is pretty much as easily done. Your employer wants to be informed as to some coke-business. So, you take your car, and go to talk to a certain person - who, of course doesn't want to tell you about this, and starts kicking your ass. Kick his ass, pick up his cellphone. Now, a chase will begin - where you are hunted after by more people from this restaurant. Just keep running, jump into a car, and you have will have completed this one.
Now it's time for some jury-work. This mission's pay is 400$, and is not hard. Really, all that is needed for you to have accomplished what needs to be done, is to badly beat up a few cars - to frighten two jury-members.
Fourth mission's a highpaying one - giving you a thousand bucks. It's not difficult. What you will do, here, is make so there is a little rioting happening, outside a delivery-company. To do this, you demolish 3 cars. Those guarding the company's doors will have to be out of the place, for you to be able to go through with this - which the rioting, that you caused, will accomplish.

Hopefully this little article about gta vice city missions has given you something of value.