DS1 is 12 soon, he got the 'The Talk' from me a few years ago when he asked. We went through the Usbourne book, which was great as it went through feelings and emotion too.
Recently a doctor come into his school and talked to them about puberty and sex, out of interest i asked if she had talked to them about respect, he said she hadn't. I then, briefly spoke to him that when he was older, and got the feelings the doctor has just talked to him about, it was very important that no matter how strong his feelings were about a girl that he needed to understand that she needed to feel the same and wanted to do the things he wanted too. Mentioned that even if all his friends said they were having sex he shouldn't feel he should too, nor should he make anyone feel bad for not.
he's still quite young (all seems a bit yuck to him) but what is the best way to talk to boys about respect and consent?