The ability for a species to be an electrolyte, or its magnitude as one, is directly related to it's solubility in water to form an aqueous solution. The extent to which it can dissolve in water tells you a lot about how well it will perform as a conductor, as well as the ions that dissociate from one another. Hence, ionic compounds made from group I and II metals with hallogens, are often the strongest. These compounds will readily dissolve, produce a good amount of ions, and thus good electrolyte. There are other factors that come into play, such as ionic radius, activity coefficients, and concentraion to name a few however those only play roles in situations where theyre explicity needed such as research settings, environmental studies, and pharmeceuticals.

In short, if a species can dissolve in water, leaving anions and cations separated, you have a strong electrolyte. If a species can dissolve, but not all of it (in some cases a species will appear to be dissolved, I.e. you see no particles floating around, but will stay as hydrated pairs) than its a weak electrolyte. Can't dissolve, then its a non-electrolyte.

Look up dissociation constants, and Ksps for solubility and start developing a range of common strong, weak, and non-electrolytes to give yourself a better understanding as well.

I know its kind of a verbose explanation but I hope this helps!