Here is a buffet of various tips and techniques you can apply when pursuing photography and/or astronomy!

In normal daytime photography, remember to stop down your lens one or two stops from wide-open or the fully closed down position.  This allows you to avoid lens diffraction and obtain more resolution.  Every lens has a "sweet spot."

With "astrophotography" you would want to keep your aperture "wide-open" in order to suck in the most amount of light (photons) because we are trying to exposure for very dim celestial objects at extreme distances.  Now, it is still a good idea to close down your lens aperture one-stop from wide open to decrease optical abberations but you must remember that you may need to balance it out by increasing your ISO by one stop.

For captures of deep-space objects like galaxies, nebulaes, star clusters, comets and the milky way, it is best to shoot from the darkest site you can find away from any light pollution.

Learn how each of your lenses work.  What are their "sweet spots"?  Learn each lenses angle of view and focal length.  Learn the pros and cons to prime lenses versus zooms.  

Always invest your money into your optics.  Purchase a good camera but the most affordable high-end lenses you can find.

Shoot in RAW mode over JPEG.  RAW allows you to capture all the exposure data and gives you the best resolution and full editing control of your images in post.

Learn the basics of weather and how to anticipate weather changes so that you will be ready to capture that stunning atmospheric skyscape weather it be severe weather or a beautiful cloud formation.

When doing night-sky photography, always used "red" light in order to preserve your "night vision" and so that it helps preserve everyone elses night vision and does not interfere with photographer's exposures as white light does.

Long exposures require a sturdy tripod and a remote shutter release.

Use different colored lights to illuminate the landscape to add visual interest to your celestial skyscape.  This is called "painting with light".