Scientific photography should be regarded as a scientific experiment: rigorous, repeatable and reproducible.
To do so, it should meet, at minimum, these three primary criteria:

White balance manually set

This setting is made to calibrate the colors regardeless the light specificity. Most of the cameras take pictures with an automatic setting : light can be misunderstood so the white would be a little bit yellow or red. In addition, if you take two separate pictures with Automatic White Balance you can obtain two different results. This is not acceptable for scientific photography therefore AWB should never be used.
Here is an example of how to set the manual white balance with a pentax camera. White balance can be set up before the shot (if you shoot in JPG) or after (if you shoot in RAW).

Size index

A size index should always be present on the picture. Depending of the subject, you can add a ruler - on which you can read the unit (metric if possible) - or any other size reference that can be clearly understood (a match extremity, a pen, an adult human, a car…)

In order to avoid perspective distortion, be sure to put the size index on the same plan than the subject.

Contextual photography or sketch to understand how the photograph was taken

The more informations you can give on the way you took a scientific picture, the easier it’ll be for other persons to understand and reproduce the picture.
Brand and model of the camera, general settings (lens used, aperture, speed, ISO), light nature and possible pictures modifications must be told.

A good way to do it is to take a photograph of the method you use to took the photograph. This is the contextual photography. Quality and rigor dont matter here, you can take the picture with a smartphone.
Very little hardware is required to obtain a quality picture.
However, the final result can be vastly improved with a finer camera and better accessories.
When properly used, a USD600 camera can produce an excellent result. It will not allow you to print on an A0 support, this is what USD60000 cameras are designed to do! While various types of software can be used as well, this is not the top priority for scientific photography.
Remember that there is lot of barriers on the light path, and each one can corrupt the final result. Be aware of these barriers will help you to interprate a picture with a critical mind.