Based　on　the　localized　surface　plasmon　resonance　(LSPR)　of　metallic　nanoparticles,　plasmonic　nanosensors　have　emerged　as　a　powerful　tool　for　biosensing　applications.　Many　detection　schemes　have　been　developed　and　the　field　is　rapidly　growing　to　incorporate　new　methodologies　and　applications.　Amidst　all　the　ongoing　research　efforts,　one　common　factor　remains　a　key　driving　force:　continued　improvement　of　high-sensitivity　detection.　Although　there　are　many　excellent　reviews　available　that　describe　the　general　progress　of　LSPR-based　plasmonic　biosensors,　there　has　been　limited　attention　to　strategies　for　improving　the　sensitivity　of　plasmonic　nanosensors.　Recognizing　the　importance　of　this　subject,　this　review　highlights　recent　progress　on　different　strategies　used　for　improving　the　sensitivity　of　plasmonic　nanosensors.　These　strategies　are　classified　into　the　following　three　categories　based　on　their　different　sensing　mechanisms:　(1)　sensing　based　on　target-induced　local　refractive　index　changes,　(2)　colorimetric　sensing　based　on　LSPR　coupling,　and　(3)　amplification　of　detection　sensitivity　based　on　nanoparticle　growth.　The　basic　principles　and　cutting-edge　examples　are　provided　for　each　kind　of　strategy,　collectively　forming　a　unifying　framework　to　view　the　latest　attempts　to　improve　the　sensitivity　of　nanoplasmonic　sensors.　Future　trends　for　the　fabrication　of　improved　plasmonic　nanosensors　are　also　discussed.　©　2015　The　Authors.　Published　by　Elsevier　Ltd.