Steps I use to make world on FreeBSD:
1. Install cvsup-without-gui
# cd /usr/ports/net/cvsup-without-gui

make install distclean

2. Update the source files
# cvsup -g -h <cvsup-mirror> /usr/share/examples/cvsup/stable-supfile
3. Configure a kernel
See Configuring the FreeBSD Kernel in the FreeBSD Handbook
4. Grab the Makefile
# mkdir /root/make

fetch wp-dev.clarksys.com/freebsd/Makefile

5. Make World
# make world
6. Make your Kernel
# make -DMYKERNEL=<your kernel name> kernel
7. Merge the updated configuration
# make merge
That's it, you now have a freshly updated system.
Check out the FreeBSD Diary for a more indepth look at the make world process.