My son now 3 was a horrible sleeper from birth. By six months he was still waking up 3-4 times at night. He also needed to be held, nursed and rocked to sleep which took up to 45 minutes each night. He wouldn't nap in his crib, etc. My pediatrician recommended I put him down still awake, but he hated it and I had a 3 year old (at the time) at home to deal with too, so I never did it. I kept thinking, one more month.... one more month too!
One weekend when my husband and I were both home at bedtime, I implemented the Ferber sleep method. Some people call it "crying it out" and I know some people think it's "cruel" to babies, but the method is much more nuanced than that so I think parents should do whatever works best for their baby and their family. The process is, you put the baby down drowsy and then check in on them at various intervals, which increase as the night(s) of training go on. The book does recommend that if your constant coming and going is making the baby MORE upset, you should stretch it out. The first night my son cried for 45 minutes. I was in tears and my stomach was in knots. The next night 15 and the next night 5.
The change was miraculous. Not only was he able to settle himself to sleep, but he started sleeping 7-8 hours overnight as well. I can't explain what a HUGE positive difference that was to my family. I was able to give my 3 year old a proper bedtime, with stories, in her room. My stress level plummeted and I was able to sleep through the night for the first time since I was pregnant! I am a strong believer in helping our children develop good sleep habits, for some babies it comes naturally and others need help. So as hard as that weekend was, it was totally worth it. To this day, my son is the BEST sleeper and ALWAYS sleeps through the night. So good luck!