I know you've had loads of advice, but if you want a little more....
I was blessed with a dd who starting sleeping through the night at 5 weeks (with me sneaking in at 11pm for a dream feed). My problem was the same though, getting her to settle and drift off. I used the "pick up, put down technique" after seeing it on a television show. It worked a treat in just 3 nights!
It's exhausting but so worth it. After bathtime and a bottle/cup, give her a kiss and cuddle, say "it's only bedtime" and put her in her cot but stay in the room. If she cries, count to 10, pick her up (NO kisses or cuddles now) and say "it's only bedtime" and put her back in the cot. Again...stay in the room. If she cries again, pick her up....you get the picture right?
I did this for three nights and when she was calm I moved away from the cot, but stayed in the room. The first night I was in her room for almost 2 hours before she dropped off. The second night it was around 45 minutes and the 3rd night she went down straight away.
The trick is to give her absolutely no stimulation once you have put her down. Every time you pick her up, the only thing you say to her is "it's only bedtime". Also, there are no kisses or cuddles. Apparently it works because the child feels secure knowing you are there. Although honestly, I don't care why it works, it just does!
Definitely give it a try. It is exhausting like I said, but since we did it, my dd goes to sleep at 8pm and sleeps through until 8am (she's a year old now). It's brilliant! Good luck.