Actually, the militaristic trait only helps in normal unit promotion (conscript -> regular -> veteran -> elite) and doesn't help directly with leaders. What militaristic civs are great at, though, is racking up a ton of elite units fast. You have so many that getting a leader is almost guaranteed. Thus, militaristic helps indirectly.
Use your elite units in battles you're pretty certain they will win. Be careful with them - protect them... DO NOT leave them out in the open, vulnerable to counterattack, since the AI will target them. Since there is a 1/16 chance of spawning a GL from an elite unit victory (1/12 with the Heroic Epic), it's all about fighting a lot of battles with elite units.
I have discovered that the militaristic trait, if used properly, is extremely valueable. I used to play as a "builder" and therefore ranked militaristic near the bottom. Now I absolutely love playing as Japan. Combine aggressive, early warmongering with militarism and ooh-la-la, GL's aplenty.
It is true that the units with blitz capability are the best leader generators (tanks, mech inf, modern armor). They can fight more battles, get promoted to elite faster because of it, and you often have TONS of them. Once you have tanks, you've got factories, which means you can pump them out in 2-3 turns in good cities.
-Arrian