I am using an iPhone4 running iOS7 and a Windows 7 Home Premium computer. The steps should be similar for other devices and operating systems.
1 Have both the computer and iDevice turned on
2 Plug in the cable for the iDevice to an available USB port, the computer should make the “USB device inserted” sound and the iDevice should “ring” twice
3 Windows may need a minute to load drivers if this is the first time
4 Unlock your iDevice if needed
5 The iDevice should ask if you trust this computer. If it’s your own computer, tap “Trust”
6 If a Windows Explorer dialog box does not open, click on the Windows Explorer icon in the Taskbar or click the Start button, All Programs, Accessories, Windows Explorer
7 Under “Computer” / “My Computer” / “This PC” there should be a a device called “Apple iPhone (or iPad),” click on it
8 An icon marked “Internal Storage” should appear, double-click it
9 Next is an icon marked “DCIM,” double click it (I think it stands for Digital Camera IMages)
10 Then you should see a folder marked with a random looking name, double-click it. You might see more than one if you are using a newer version of iOS, those may be folders ordered by date. You will have to double-click each one to see what files are inside
11 You should then see photos. From here you can select the ones you want with your mouse and using the
key to select a range or the
to select each file and then right-click on one selected file and click on
12 Click on the “Pictures” folder in the left pane of the “Computer” window.
13 If you need to, create a new folder and name it. Either by clicking the New Folder button, right-clicking in a blank area and selecting New > Folder.
14 In a blank area of the new folder, right-click and click Paste. Your file(s) should move from the iDevice to the new folder. Continue until the files you want are moved.
15 Close all windows you no longer need.
16 Right-click on the USB Devices icon in the System Tray to eject the iDevice. If one isn’t there, you can just pull the cable as long as both devices are finished with the files transfers. If unsure, wait a minute or two.
17 When transferring a large number of files, a dialog box will appear telling you the number of files and an estimate of how long the transfer will take.
Just a quick run down.