They're very easy to set up if you have an outdoor hose faucet. Dripworks is an excellent source. Request their free catalog; they'll also help you design your system (easier if you fax them a drawing).

If you don't have an outside faucet but your bathroom or kitchen sink has a screw-on filter, you can probably buy an adapter from your local hardware store (bring the filter in with you). Get the quick-release kind, which leaves a small tapered adapter screwed permanently into your sink that lets you use it normally when there's no hose attached.

Either way, you'd want to attach your timer to the faucet (the Orbit LCD Battery Timer is a good choice), then a filter, a pressure regulator, the hose, and an adapter for the start of your drip "mainline" (usually 1/2" tubing; use "Easy Loc" fittings). That will prevent the hose from being under pressure except when you're actually watering.

It's best if you can arrange things so that any indoor connections that may drip a little are sitting in a sink or bathtub. Dripworks sells hose elbow adapters and short lengths of heavy-duty hose that can remain under permanent pressure; these may help in tight situations.

I don't have a hose hookup on my patio, but I am going to experiment this summer.
I am going to purchase a basic drip system for with about 30-50 adjustable drippers. Then I am going to purchase a pond or fountain pump that will put supply about 10 or 15 pounds of pressure, and figure out a way to connect the pump output to the 3/4 inch hose of the drip system. The pump will go into a covered 5 gallon olive bucket, that I will fill up with water. I will then plug the pump into an appliance timer, and the timer into a wall. I figure I can set the timer to turn on the pump for 1/2 and hour 4 times a day. If a plant is getting too much water I will lower the flow on the dripper. I figure this way I can have the system water my tomatoes & my herbs at the same time, and keep all my plants happy.
I will keep you posted of my results.

Benedita..
Well are you in a co-op or a rental...
if the outsideis near the water why not just run a line out to it... and you'll have a bettertime of general watering as well as a drip system... it's not alll that hard or disruptive... Perhaps I can help... Gordon

I have about 15 container plants on my deck, all hooked up to a drip irrigation system from www.dripirrigation.com. Works great. They have a basic kit to start. Just make sure you get the controller/timer.

Let us know how it works out, benedita! It sounds like a good system, and has the advantage that everything's outside.

These guys sell pumps, reservoirs, tubing, and adapters, though their pumps need to be protected from moisture. They might be able to help you put your system together, if you haven't already.

I built my own drip watering system for my Manhattan terrace garden after getting a couple of outrageous bids from professionals. I use the weighted drippers from Chapin Watermatics located in (where else?) Watertown, NY. They are very nice, dependable folks.
I've used this system for four seasons now and have had no troubles. One must be careful, when pruning, not to snip the tiny dripper hoses.