Hi,
I found out the day before my son's first birthday that I was having another child... and I was still nursing, and wanted to for at least another year. So, I had to completely change my mindset before I started weaning him, because I didn't want to stop nursing yet. That would be the first thing I would suggest: Make sure you really want to stop nursing him, or it'll be a lot harder, if it happens at all.
My son would also nurse himself to sleep. I think what we did was cut out all of the "extra" feedings- the times he wanted just a snack, and only let him nurse at certain times- first thing in the morning, before the naps, and before bed. When it was down to that point, I think we cut out the morning feeding first. After that he stopped taking his first nap at about the same time I needed to cut out another feeding, so that was very convenient and lucky for me. To drop the naptime nursing, one day he fell asleep in the car, the next day I "just happened" to be doing errands at naptime, and his daddy had to put him to bed. After those two days, he decided that he didn't need to nurse then anymore, and that was the end of that feeding.
When he was 15 months old, I dropped the last, before-bed feeding. I changed his bedtime routine a little, made it more "toddler" than "baby". We started saying goodnight to the stars, and reading a few stories, and then I put him to bed without giving him the chance to nurse. I think I cried more than he did.
Take your time, and don't try to rush things, and be consistent. If you accidentally skip a feeding one day because you're out or whatever, don't let him nurse at that time the next day. It usually took my son two days to adapt to dropping a nursing time. It'll be harder for you than your child.