  We have studied the physical properties of a sample of narrow-line Seyfert 1
(NLS1) galaxies, and present a summary of our previous results, and new
results. In particular, we have previously shown that (1) the locus of NLS1
galaxies on the M_BH-sigma_[OIII] plane does follow the relation of non-active
galaxies after removing objects obviously dominated by outflows as evidenced by
their [OIII] core blueshifts. We have (2) identified a number of so-called
'blue outliers' with large outflow velocities revealed by their emission-line
kinematic shifts. We also (3) present new correlations and trends which link
black hole mass, Eddington ratio and physical parameters of the emission-line
regions.
