- send enough ally requests on first turn, so that you won't get outnumbered (first turn ally reqs are often very important)
Are you mad? This is the basis for ally-fuggery!
- learn to properly wall your cities and stuff (most noobs don't do this although it's very effective for your defence)
Yes!
- don't forget to use transports to be faster than your enemies (many noobs don't use them too or only rarely)
Not necessarily transports... depends on funds and other expansion methods... walking! Rule should be: expand fast but consistently.
- always have an eye on the SP of the players, the game duration and the diplomacy (else it easily can happen that you attack the wrong people)
Not necessarily SP, but troops and countries (cities) hold! High SP can be due to fast but not consolidated expansion.
- don't be too passive and don't ally practically everyone or else you easily can lose by SP (attacking other players brings more SP than attacking neutral units/cities)
Yes. But this one contradicts your first point!
- use Perfect Defence as a strategy and spam a lot of infantry with it (it's a very good alround strategy and easy to use for beginners)
Basically yes. But for 50k Worldgames (common games among low ranks) there are better strategies (specially for fast expansion). But basically yes!