I always took DS up for a bath for 10-15 mins, got him out wrapped up in a towel and gave him a bottle.
Once he was down about half the bottle, I'd unwrap him and give him a baby massage, nappy and sleep-suit, then give him back his bottle and take him up to bed.
Mobile on, kiss and "I love you", and out.
This started between 5:30, 6pm.
That'd be him asleep for a good few hours then. His dad was practically nocturnal anyways, so I'd feed him around 10ish and go to bed, his dad would feed him around midnight and 3am then go bed, then when he'd wake around 6am I'd get up an feed him.
Same as others, I always made sure to differentiate between night and day. Night time was quiet, dark, general "shhh, baby sleeping". Daytime he'd just nap in the living room, daylight, I'd hoover round him, clatter around in the kitchen... Did that pretty much from day one. Started bedtime routine around four weeks.
All in all though, I think I just got lucky there, and that was how he was happy. The best you can do is try the things we've all said here, see what works/doesn't, and go from there with whatever fits your LO. Xx