If you're looking for a crash course on him as a political thinker, you could check out the selections that seem of interest to you from his Essays, Moral, Political, and Literary[0]. If you want a more specific list (and a reasonably coherent reading order):

* 'That Politics may be reduced to a Science' ("It is a question with several, whether there be any essential difference between one form of government and another? and, whether every form may not become good or bad, according as it is well or ill administered?")

* 'Of the First Principles of Government' ("Nothing appears more surprizing to those, who consider human affairs with a philosophical eye, than the easiness with which the many are governed by the few")

* 'Of the Origin of Government' ("Man, born in a family, is compelled to maintain society, from necessity, from natural inclination, and from habit.")

* 'Of Parties in General' ("As much as legislators and founders of states ought to be honoured and respected among men, as much ought the founders of sects and factions to be detested and hated; because the influence of faction is directly contrary to that of laws.")

* 'Of Passive Obedience' ("The maxim, fiat Justitia & ruat Coelum, let justice be performed, though the universe be destroyed, is apparently false, and by sacrificing the end to the means, shews a preposterous idea of the subordination of duties.")

* 'Of the Coalition of Parties' ("Liberty is a blessing so inestimable, that, wherever there appears any probability of recovering it, a nation may willingly run many hazards, and ought not even to repine at the greatest effusion of blood or dissipation of treasure. All human institutions, and none more than government, are in continual fluctuation.")

* 'Of the Rise and Progress of the Arts and Sciences' ("What depends upon a few persons is, in a great measure, to be ascribed to chance, or secret and unknown causes: What arises from a great number, may often be accounted for by determinate and known causes.")

* 'Of Commerce' ("The greater part of mankind may be divided into two classes; that of shallow thinkers, who fall short of the truth; and that of abstruse thinkers, who go beyond it.")

* 'Of Simplicity and Refinement in Writing' ("Fine writing, according to Mr. Addison, consists of sentiments, which are natural, without being obvious. There cannot be a juster, and more concise definition of fine writing.")

* 'Of Refinement in the Arts' ("We shall here endeavour to correct both these extremes, by proving, first, that the ages of refinement are both the happiest and most virtuous; secondly, that wherever luxury ceases to be innocent, it also ceases to be beneficial; and when carried a degree too far, is a quality pernicious, though perhaps not the most pernicious, to political society.")

[0]: Available on https://davidhume.org/