How to get only the first ten bytes of a binary file
To get the first 10 bytes, as noted already:
head -c 10
To get all but the first 10 bytes (at least with GNU tail):
tail -c+11
head -c 10 does the right thing here.
You can use the dd command to copy an arbitrary number of bytes from a binary file.
dd if=infile of=outfile1 bs=10 count=1
dd if=infile of=outfile2 bs=10 skip=1