The neo-cons actually started out as left-wing idealists, but who saw the USSR as the greatest threat to world peace that needed to be dealt with strongly. They came to power with Reagan in the 80s and believed their aggressive policy towards the USSR was successful in its collapse.
They’re idealists who believe the key to world peace is the spread of liberal democracy throughout the world. The collapse of the USSR proved this in their minds. Their aggressive approach to foreign policy (ironically in the pursuit of democracy!) made them bedfellows with the Republicans.
They lost control over foreign policy when Bush Senior was voted out and campaigned throughout Clinton’s two terms for him to invade Iraq and remove Saddam from power. A summary of their ideology (on foreign policy) can be seen in this article by Robert Kagan and William Kristol (two of the most influential neocons), it’s almost like their manifesto:
http://www.newamericancentury.org/def_natl_sec_pdf_07.pdf
They believe that where possible, any non-democratic government should be overthrown one way or another and replaced with a liberal democracy, that would naturally be supportive of the USA! They are quite ideologically driven and rabidly hate anything that isn’t liberal democracy. It’s almost like me hating Sheffield W*dnesday just because that’s how I’ve been brought up! Just look at how they view the Chavez regime and the fear they seem to have over anything mentioning the word 'socialism'!
I don’t necessarily think that promoting the spread of democracy is a bad thing, even our version of liberal democracy is a better form of government than these dictatorships, but the flip side of neoconservatism is their unwavering support for Israel. Neoconservatism is infested with Zionists who see no difference between US foreign policy and Israeli foreign policy, and it is support for Israel that takes preference over their aim of spreading democracy. So when Hamas were elected in Palestine, they cut off support for the PA because they see Hamas as a threat to Israel.
They want democracy, but they want their own version of democracy with who they chose to be the leaders of these new democracies – so in short, pretty much nothing like democracy! To them, democracy is a system of government and economics, rather than governed by the people. Their policy of aggression to implement their plans for democracy installation also, IMO, runs counter to the tradition of democracy and causes the natural reaction from the population - opposition (eg. Iraq)
In short, it is empire building. The method they use is the occupation of foreign land with a liberal democratic system of government, with leaders of their choice, favourable to the interests of corporate America.
(Sorry for the essay but, well, I wrote an essay on it and the above is a summary!)