Physical Tools
8 x 42 Binoculars are the most common used for bird watching it strikes a good balance between brightness + magnification and weight for carrying. The first digit 8 is the front lens width (higher means bigger lend and brighter image) and the second number is the effective magnification. An increase in either would increase weight.
20x to 60x spotting scopes are usually used for bird watching. These have greater stability and magnification than binoculars, but also greater weight since they are commonly supported by a stand.
There are many different guide books that are region specific. Some of the most commonly used are Audubon and Sibley guides. Many of these books come in small form factors so that they can be easily carried into the field.
Tips
Mornings and evening will have more bird activity.
Pick a place with a diversity of plants or near water ways wait and listen.
Learn the bird calls.
Small birds often fly in a semi reliable loop. If you spot a bird and miss it may return to that location another time or day.