Your comment about your best effort on Deity, lead me to think about science and population. On Deity, the early game is very important (to be able to catch up in techs) and I try to follow roughly the following "timetable" myself: 1. Your capital should be pop 4 around turn 20-25 on standard speed (obviously a pop ruin is very helpful but try to secure one tile with 3 food as soon as possible) and steal your first 2-3 workers, 2. build your settlers as soon as your cap is pop 4 (with liberty you can wait a bit longer), 3. Have 3 expands by t50-55, 4. Try to set up a trade route with a nearby AI, 5. Build NC on t80-95 and 6. Have a total pop of at least 25 by t100 (like capital 9, first expand 7, second 5 and third 4 as an example). 7. Get to education by t100-115 and build your universities soon after, 8. By t150 you should be on par with the AIs at the latest. The better I grow my cities the better my science game becomes and thus it opens up all kinds of possibilities. Any peaceful victory should be reached roughly by t300.
In the thread Enjoyable Diety Games I have described the early game build order in most games this year (EDGE#41 onwards) and exactly for the purpose of providing a benchmark. Keep in mind that there are many better Deity players than me, but the benchmark above is a "survival level" that will set you up to win most Deity games.