While I respect those who don't want to let their babies cry to sleep because they don't want the baby to feel abandoned, (or even just because it breaks their own heart!) I feel confident that my babies did not feel that way. When you are consistent about how you handle sleep time, it only takes a few times of "crying it out" in order for the baby to get used to falling asleep on his own. After that, naptime and bedtime are peaceful, enjoyable times rather than battles. And I'm not talking about him battling you, although that may happen when he is older if he doesn't know how to go to sleep on his own. I'm talking about him battling sleep. After our good-night song and hugs and kisses, my babies would sometimes reach for their crib. Consistency is key, though, especially in a bedtime-naptime routine. An enjoyable, almost inflexible routine helps him (or anyone, sleep experts say) prepare for sleep. If you vary the routine, a child will fight the final step of actually lying down to sleep. (One more story, another drink, go potty again, etc. ad infinitum)
Here is a routine for a six-month-old: Baby yawns, fusses, or rubs eyes. "You're sleepy, aren't you? Let's go get your blankie." Pick out a short board book. Cuddle together and read it. "Time to go night-night!" (Say firmly but very positively, as if this is a wonderful thing he is going to do.) Walk to crib. Stand in front of crib cuddling and singing a song (same one every time!). Lay him down in crib with one last kiss. "I love you, baby!" Walk directly out of the room and almost close the door. (I like to be able to see in without being seen.)
A big part of this working over the long haul is your confidence that you know better than he does when he needs to sleep. If you waver, he will doubt that it is really time for bed.
Also, watch for signs that he is getting sleepy, and do the routine before he's about to fall asleep. If you wait till he's about to fall asleep, then he is overtired and you've actually interrupted the falling-asleep process and he has to start over.
The Healthy Sleep Habits book will have lots of other good stuff in it. One last thing, though: beware of "the books" and magazines in general. (And us advice-givers!) We don't know your baby, but you do! If YOU think he needs to nap more because a book helped you see that he is cranky or falls asleep in his high chair, then you need to do something, but not just because a book said so. Enjoy those baby cuddles for me - I miss them!