There's a lot of people out there that don't know much about putting a baby to sleep. It seems like a foreign concept to them. Babies generally like a lot of attention and they're typically not sleeping long hours, so you're in a touch situation as a parent.
There are a few rules that you want to follow in this whole process of putting baby to sleep...
Routine: Everyone, even babies, have internal clocks. If you go to bed at the same time, you're likely to feel that way at exactly the same time. It's just the way our human biology works. If you act inconsistent with your babies sleeping patterns you run the risk of making the whole process difficult.
Environment: Just like adults, you need an environment that helps with the process of sleep. Generally it should be quiet. No baby is going to sleep if you have older children running around and making noise.
Have a Night Light: It's sort of different for a baby, than it is for a child that is a few years old, but it's good to have around. It makes things easier for you when you're checking up on them.
These are all important parts of putting a baby to sleep, so make sure you follow them. Remember to always be consistent. That is the most important aspect I want to get across.