Which mode?
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Which mode?

Keep the camera in fully 'Automatic' mode, which is usually the only option on the mode dial that's green (the 'Mode Dial' will usually have P, A, S, M options among other icons such as a floating head for the 'portrait' preset, some small mountains for 'landscape,' and so on). On Olympus cameras, there's a setting called i.Auto on the mode dial, and on Fujifilm cameras, you'll want to flip the 'Auto' switch, or on the lower-end models, go to 'SP+' mode.

The half press

Unlike a smartphone, most interchangeable lens cameras provide you with a two-step process for taking a single picture. You'll want to press the shutter button (it should be logically placed under your index finger while you hold the camera) very lightly - we call this a 'half-press.' What this does is signal to the camera that you're intending to take a picture, at which time it will focus on whatever is in front of you, and it will pick an exposure (it will decide how bright to make the resulting image). Press the shutter down all the way now, and you'll be greeted with some sort of shutter noise indicating that a photo has been taken. Yeehaw!