Most times the reason you get destroyed/fail to militarily dominate is because you wanted to build 'neat' things like Wonders or temples and such in cities. 

If you're doing that, you're not building military units...if you're not building units, you'll be easy pickings for AI civs that think you're weak.  So you're constantly under the 'empire or war machine?' gun.

If you start with the military camps between 'real' cities, you can crank out enough units to make people fear you!  And you can build settlers faster to boot, so you can expand faster, get more camps, more military and more other cities. 

And the added bonus is, that later in the game, as you start drawing down your camps by making workers, you'll have the monstrous labor force necessary for railroads and pollution cleanup.

The reason that Civ IV has changed back to the fatX philosophy...i.e. you can't draw down and abandon cities...is because this strategy...a modified version of ICS (Infinite City Sleaze) is the magic bullet.  You will always win using it.  Game designers hate it when you find the strategy to consistently beat their blind monkeys...er AI's.  So they had to nerf it with Civ IV

I just don't think new players are ready for this...  but then again if they start with it...

I couldnt agree with that.

If a Civ is far away, especially in early years they can jump up and down and declare war as much as they like..still not going to get you.

For instance I try and keep from trading my map or giving my map until as long as possible.  It has some trade value especially if another Civ hasnt been wandering all over your land and as soon as you trade it, a) it looses its value and b)you start to find all the nearby civs sending hordes of settlers into your lands to grab prime real estate you have yet to settle.

Land is the key, dont give it away and dont make it easy.