Im pro gay marriage, so I'll just use that statement.
Introduction: Reference to this hot topic.
"Lately, there have been a tremendous amount of discussions regarding the concept of man to man marriage..." etc
Thesis statement at the end of the introduction.
"Gay marriage should be globally accepted."
Body: 3-4 arguments for your statement, optionally 1-2 against your statement WITH a counter.
+1) Love is unconditional.
"The aspects of love vary greatly, whether there is a difference in age, interest or religion. Then why would a similarity in sex evoke a problem?" etc
+2) Gay people are just like us.
"Another significant point is that homosexual individuals are fully developed human beings. They are not some sort of crab-like aliens, covered in slimy goo, waiting for a moment to occupy the world. No, to the contrary, they belong with us." etc
+3) Homosexuality was part of everyday life in the ancient times/is found in other species as well.
"Nor the Romans, nor the Greeks, the great founders of society, were unfamiliar with homosexuality and it was not an uncommon concept." etc
"Other animals, like [animal] and [animal] can easily sustain themselves in a gay relationship. It has been embedded in their nature." etc
-4) Not accepted in religion.
"One could argue that a holy script suggests that homosexuality should not be accepted." etc
C4) But religions are just limited to certain groups of people.
"It is not the case that all religions forbid gay relationships and not is a particular religion present with every human." etc
Conclusion: Summary, prospect/suggestion.
"All in all, [repeat thesis statement]. Since [Arg1], [Arg2] and [Arg3], it can clearly be stated that there is nothing wrong with homosexuality. Even though [-Arg4], this can simply be countered by the fact that [CArg4]. Therefore, let us look forward to a future with global acceptance of gay marriage, let us invoke a communial emotion of euphoria...