1. Take camera outside. I used an Olympus E-PL-7 (link).
2. Find pretty flowers.
3. Set camera focus, shutter speed, and aperture (F-stop) for your subject.
4. Slow shutter speeds (ex: 1/15) let more light into the camera sensor and are great for low-light and night photography, whereas fast shutter speeds (ex: 1/250) can freeze motion.
5. Aperture (F-stop) will control the depth of field, or the portion of a picture that appears sharp. If the aperture is very small (ex: f/22), then the depth of field will be larger. If the aperture is large (ex: f/1.4), then the depth of field will be smaller.
6. Take pictures.
7. At home, open pictures in Adobe Lightroom.
8. Select filters and develop settings to achieve your desired look. For a professional style, try to reduce any extreme peaks in your histogram. Aim for an "S" shape in the Tone Curve for a balance of highlights and shadows. Sharpen and mask any details as necessary. Be sure to zoom in and inspect each new effect to avoid over editing.
9. Export as a JPG by right-clicking on the image's thumbnail.
10. Post on Instructables :)