Uncle JJ it goes something like this
step 1, get the great wall asap. hopefully you get a 2nd city and 2 workers out in the process. (philo civs with mining are good for this)
step 2, beeline for alphabet while your great spy points accumulate
step 3, send great spy to the capitol of whoever the tech leader is likely to be (financial civs etc.. we know mansa would be a good target

) use the infiltrate city option and get 4000-9500 espionage points against that civ(depending on game spd)
**right now that doesn't scale over time.. so weaker later. scaling with speed is fair because techs are more expensive**
step 4, research alphabet and begin producing spys. 3-5 will do nicely. beeline them for the enemy capitol as they get produced. each spy is to wait 5 turns, then perform the steal technology mission. each tech has an espionage cost roughly equal to its beaker cost. -50% for waiting for 5 turns. its even better if you have open boarders with the civ. and you get a discount for having so many more points into espionage then they do.
from here, you have enough points to steal usually 4-9 techs. you also get to see everything in their cities and what they are researching. so research other stuff knowing you will steal their techs.
when doing this, make sure to allocate your other espionage efforts to another civ, the civ that you are infiltrating doesnt need further points for a while.
almost broken levels of pwnage
NaZ