Lots of answers (factors) for your very generic question.
Bouyancy is also dependent on the salinity of your environment (I use a tad more weight in the Gulf of California (saltier) than in Key Largo), your physical makeup & size, then add your gear (ie AL tank vs. Steel tank), and add what webmonkey said about fit & age of suit, etc. Not to mention that the "average 3/2 fullsuit" can vary depending on size (xs = less neoprene than xxl = more neoprene).
My ex & I both dove in 3mm stretch suits and used the same 8lbs in the same waters, however he weighed 200 all muscle, I weighed 130 typical female fat deposits (those that make us curvy make us floaty).
Experience also effects your bouyancy/lead. The more relaxed and practiced you are in the water, the less lead you need. My lead (described above, started out at 11lbs in that suit and after 50 dives I had tweeked down to 8lbs with better bouyancy control (and maybe a bit of new wetsuit compression/age too).
What are you currently diving? If diving 7mm, drop about 30% or more of your current lead, if diving in just a bathing suit, add a few pounds, etc. Adjust by trial and error.
...There's no way to know without you doing a buoyancy check while wearing it.