When Spain accidentally found the new world, they did not have just an extensive experience in conquest, strategy and dealing with other cultures they adopted a very radical different approach compared to French and England:
Spain and Portugal has en extensive experience in fighting, reconquering, evangelizing and dealing with a foreign culture: it took many centuries to push back all of the Moors/Arabs from the Iberian peninsula during the reconquista. Now it is hard to imagine, but back then Spain and Portugal were both the world's strongest superpowers back then. until England and France surpassed them some centuries later.
After the conquest of a territory, all natives would be evangelized and converted to Christianity, making them subjects to the monarchy and treated as equals at the oversees provinces (see Ley de Indias in Wikipedia)
Coming from a background the multiracial of Roman Empire and having been invaded several times by Germanic tribes, Arabs etc, they had no issue mixing themselves with other races (see Mestizage in Wikipedia, be aware that the article in English for Miscegenation doesn't honor enough the largest racial mixture ever produced, during the Spanish Empire). As difference the French and English suffered from common Central European ethnocentrism (nowadays would be known as racism), and fought and exterminated natives when they could. A an example of such brutally difference, centuries later Thomas Jefferson sold his own son with a native as slave without any recognition.
This last point became extremely important as conquistadors often married nobility of the natives, normalizing social equality between both groups of people (social differences depended on being a servant or having a royal title rather than race), and American royal societies were invited to take part in Spain's Court and have some power oversees.
That fact alone made Spaniards and much more effective in building a multiracial empire with the help of the own natives who often wanted to defeat other tribes that oppressed them for centuries. For more information read about the conquest of Mexico and how many tribes joined barely 150 Spaniards marching against Tenochtitlan (1 million inhabitants) and how Hernan Cortes sons became the first Mexican and a full right citizen.
If I had to summarize: Spain built a generative Empire, whereas England only tried to build predatory empires, and needed quite a long time to advance socially, military and technologically to achieve that since built its colonies in America, first with Catholic slaves (mostly Irish) and then with African slaves to replace natives, whereas Spain built upon the existing societies.
These points are often missed in Anglo-Saxon countries, since the study of historical empires which is somehow felt as if it was the same "current country", this for sure is felt as part of politics or social identity of societies, and often military and strategical decisions of the past conflict with the present society. There is more information of that phenomenon on the Black legend article at Wikipedia which became a common tale during English Second empire, and after the repeated failures of France in America.
Related topics of interest, can be found in the Wikipedia articles:
---- Edit for all the comments accusing me of lying or whatever -----
P.D. Some people on the comments accuse me to lie or something, please, first do not project self identity to historical facts from almost half millennia ago and check the sources by yourselves. Giving civil status to the natives was just a natural consequence of the long reconquista process were it happened already massively and thanks the Catholic mindset, thanks to the Catholic Queen Isabel and later thanks to the Pope who insisted on the fact that natives had soul. Therefore all them should be treated as innocent souls since they never heard the evangelic texts before, so a high paternalist attitude was pushed politically.
Also regarding racial-enslaving laws, that was not the case, check the first black person arriving to America (Juan Garrido) as free man and conquistador, the first black university professor in Europe (in Granada, Spain , XVI century) or the first interracial weddings, Catholic in the Spanish Florida. And still no utopia should be made, like all empires it condemned and restores slavery many times, and it took centuries to migrate from the mindset of ancient times to a more equal rights modern perspective, but that doesn't change the multi racial generative empire, like Romans, Ottomans or Russians. but not English, French or Dutch.
Just check the actual sources, everything Spain did was accurate, the letters from Cortes to the kings are preserved, also journals and reports were exhaustively kept preserving the Roman/Catholic tradition of documenting everything like we still do in the western world (and some other cultures).
With that I will stop editing to reply the comments, these were the reasons why some empires succeeded were others could not until some new advance in technology and military strategies were made. Nothing to do with competition of nowadays nations.
