You already pay for numerous services & luxuries that decline in value far faster than a photograph.
Creative Service Professionals have the equipment and expertise to provide the service you seek on demand. Put simply, they are saving you time & money compared to buying the gear and learning to do it yourself.

RAW or JPEG?
A camera RAW file is a digital negative containing minimally processed data from the image sensor. These file can appear flat and desaturated in color until processed. Compared to JPEGs, they retain the maximal potential for editing and retouching.
JPEG images are smaller files and have preset edits made in the camera with less flexibility for color correction, white balance manipulation, and general retouching as with RAW files.

Aperture
The size of the hole or "iris" of the camera lens is measured as an "f-stop" (f1.2 - f32). A smaller aperture = a bigger hole (f1.2 - f4) allowing more light to hit the camera sensor but resulting in a shallow depth of field (thin line in focus).
Low f-stop lenses (f1.2) contain significantly more glass making them far heavier with potentially slightly slower autofocusing speed than a zoom lens or lens with a higher minimum f-stop. Extra glass, extra light, and more pleasing bokeh right out of camera means a dramatically higher price.

Shutter Speed
How long the shutter opens for light to hit the sensor influences how movement appears and how well-exposed an image is. Slow shutter speeds of less than 1/30th of a second up to 30 seconds allow an abundance of light to hit the sensor. This will capture motion blur, light trails, and astrophotography.
Faster shutter speeds (1/500th - 1/8000th of a second) are useful for sports, planes, birds, animals, fast-moving subjects, or for freezing motion of moving subjects like hummingbirds, moving water, cars, etc. Because the shutter is open for very short periods, very little light can hit the sensor. If external lighting is poor, fast shutter speeds will result in dark or underexposed images.

ISO
ISO is the volume nob for light in your photo but, importantly, is not a source of light itself. It is an indicator of how much light is present. High ISOs (1,000 -12,800) = low light. Low ISOs (100-800) = adequate to ample light.
Darker images from a lack of light tend to be inherently noisier or fuzzier. A high ISO (800-12,800+) makes this evident and is a symptom of underlying poor lighting. Raising ISO brightens the image but appears to make it "noisy" or "grainy" as a result. A high ISO reveals that there is inadequate light present rather than causing the noise in the image.

Posing & Cropping
Frequently viewed as the least favorite part of taking photos by photographers and clients alike, there is an art and continual discernment required to train the eye for poses that flatter and accentuate your subject, key features, angles, and expressions.
Poses must be understood when considering the final image crop so the subject is not cropped awkwardly or at joints breaking up the visual flow of an image. Finally, no one wants an image that feels overposed so comfort and rapport are paramount to successful experiment and movement.

Lens Choice
Image quality depends on the lens, not the camera body. Optically pure, chemically. coated glass, nano image stabilization motors, and sophisticated construction deliver the clarity, flattering aesthetic, and bokeh often desired, but at a steep price.
Wide focal lengths (14-35mm) require less working space but exaggerate distances in images and can distort subject features. Tighter, telephoto focal lengths (50-200mm) compress distance, flatter subject features, and create attractive out-of-focus blur.
Competency with focal lengths and how to make each one shine provides maximum utility for designing final images.

Perspective
Also known as camera angle, this simple adjustment dramatically shifts not only what you aim to emphasize but also that features relationship to other elements in the image. Camera angle interacts with posing and lens choice to impact how your subject appears and what sort of emotion or feeling is conveyed.
Critical to presenting your subject in the best light, camera angle will let you determine how to convey different parts of the body (face, chest, shoulders, waist, legs) to the camera. Creating unattractive thickness in a female subject or an undesirable feminine look for aman are mistakes that are often made with haphazard camera angles.

How the Camera Sees
Posing and cropping decisions, what lens you will select (if more than one) and the different perspectives and angles that will work for your subject and location are moment-to-moment considerations that affect how appealing your subject appears.
As Ansel Adams famously said about capturing an image, it's all about "knowing where to stand". This is the foundation upon which you can add poses, lighting, lens choice, camera angle, and camera settings. But what works for one photo or environment may not work for another and adjusting on the fly is preferable to extended breaks, particularly when you cannot control all external conditions.
A photographic technique that intentionally blurs parts of an image. The result being a pleasing, out-of-focus effect.
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"That out-of-focus shit in the background"
-Joe McNally
Nikon Ambassador
Bokeh
Examples of Bokeh or "Out-of-Focus Blur"

"Buttery" or "Creamy"

"Smoothening" or "Polishing"

"Light Circles", "Bubbles", or "Cat's Eyes"
Balance aperture, shutter speed, and ISO to work with the characteristics of your subject & environment allows you to reliably get the images you want.
All that said, the biggest choice is...
Shoot in Automatic or Manual Mode?
Manual Mode unlocks a camera's full potential for you to control how the images are captured under a variety of circumstances. It is not necessary to capture the images you want but provides more tools and levers to manipulate how images are produced. This is done to anticipate how processing an image will unfold given the settings used to obtain the RAW image. Automatic modes will take all or some of the control away from you.
While this reduces the learning curve for getting out and taking photos, especially when shooting JPEG, you must consider whether the control you are giving up for the sake of convenience is best for the type of images that you wish to capture. Depending on your goals and subject, you must also realistically consider whether your significant other, child, parents, or friends will be satisfied with the images you capture. This is especially in situations where you cannot recompose your subjects or control their movement.
Even the best photographers will get it right in the camera and still spend time in post-processing to bring out the absolute best in an image. RAW & manual mode, while presenting a greater learning challenge, allows you to extract all the beauty, color, and range that is inherent in the images taken. Understanding the tradeoffs will help set expectations should you forego paid, professional services and opt for doing it yourself.
Are you prepared for the full photography workflow?

Planning the Shoot
What is your subject? What will you need that camera to do? Do you currently own that camera? Will you go spend $500-$3,000 to acquire it? Should you buy new or used? Where are the most reputable places to buy?
Will you photograph subjects in different lighting conditions or will you be able to control the light? How fast or randomly will your subjects be moving? Is your lens up to the task? Do you have the right SD card to handle shooting in bursts?

Executing the Shoot
What settings will you use? Do you need more than one lens? If so, how will you choose the best one? Have an extra $500-$10,000 in your budget for that lens? If you choose to shoot in Automatic Mode, how do you know that the camera will select the correct settings?
If conditions change rapidly, are you confident in your ability to adapt? Can you have your subject pose or move again if you miss the shot?

Post-Processing
What software will you use for editing? Do you own or license that software? Are you comfortable with utilizing that software to its full potential? If not, how long will you need? What about upscaling or denoising images if you cropped the image or had poor lighting?
How long will it take to put the pieces of this workflow together? How much time are you willing to spend? What if your learning curve takes longer than you expected and you're not prepared when you need to be?

Digital Asset Management
Where and how will your images be stored after removing them from your camera? How will you organize files in your editing software for ease of use and access? Will you use a laptop or desktop computer? External hard drives, USB drives, Network Attached Storage?
RAW files, because they capture all the available information, are larger files and will fill up your storage faster. This necessitates regular purchases of addition storage. it is also wise to have second, redundant files saved at another location separate from your primary storage should a traumatic event occur that wipes your primary storage system.