MJ started to sleep through the night at about 8 weeks (like 10 hours) and then at 6 months she stopped and would wake anywhere from 2hourly to 6hourly, sometimes for 5 mins, sometines for an hour.
Now she sleeps from 7.30ish - either 10.30, 12.30. 2.30am 0r 6.30am. depends on a lot of things, last night she slept staight through to 2am and then woke cose she had a soaking wet nappy, changed her, couldnt resettle so came into bed with us (i had to work in the morning so gave up quickly!!!) then slept through til 7am (i snuck out at 5.30am).
the night before she slept from 8pm til 6.30am
the night before that she was awake twice, 10.30 (quick to resettle) and then 2pm longer to resettle.

IMO there is no way to really 'teach' this, what one baby does is not necessarily the norm. My CMHN said that its not 'normal' to sleep more than 8 hours until the age of 2... so there could be a lot more wakeful nights.
We have Not done routines or CIO. on and off coslept, but mostly in her cot in her room (no room in our bedroom for anything else!)
We could attribute nothing to the change at 6 months.

How you deal with wakeful nights is the key to getting through all these months. I see it as my baby/toddle needs me for something, be it feed, too hot/cold, comfort, cuddle or reassuarnce... she has no real way of communicating with me so she cries to let me know that she needs something.
Its my job to work it out and get her comfy again. its not goingto be like this forever, and now MJ can tell me if she needs a drink when she wakes, so it does get easier.
Just try and go with the flow and dont be anxious... yes other babies maybe sleeping through the night, but a heck of a lot are not, probably more are not that are.
This doesnt help, but do what comes naturally, if something doesnt feel right - like letting MJ cry felt wrong for me- then it probably is not right.... kwim