You gotta have good plugins to get a good sound. Below you will find links to all the good-sounding plugins you could possibly want and they’re all FREE

Some great packs of plugins:

Variety of Sound – Hands down Variety of Sound has the best free plugins I’ve found. All of them sound great, and they’ve got a little bit of everything.
Favorites (All of them): Ferric TDS, BootEQ, EpicVerb, NastyDLA, Nasty VCS, Tessla PRO, and Tessla SE. and of course the Bootsy series: NastyCS, Nasty VSD, Tabletop, NastyHF and LF.

Antress – They offer a ton of different plugins, some modeled after classic hardware processors.  They’re all great and all free.
Favorites:  Analoguer, Firechainer, Lost Angel, Deathcore, Expander, Vacuumer.

Cockos – You can download the plugin pack that comes with Cockos Reaper. For such a cheap DAW, Cockos makes some super outstanding products,
Favorites: Reaper, ReaEQ , ReaXcomp, ReaFir.

Digital Fishphones – Great selection of free compressor type plugins
Favorites: Endorphin, Fish Fillets, Dominion

Voxengo – Complicated but useful plugins of all types
Favorites – Overtone GEQ, Voxformer, Soniformer

MDA – TONS of good plugins, the only downside is the interfaces aren’t too appealing.
Favorties:  Leslie, Overdrive, RingMod, RoundPan

Other great free plugins

BitterSweet II Transient Shaper by Flux
Ambience Reverb by Magnus
Camel Crusher compressor by Camel Audio
Pushtec EQ by Leftover Lasagne
Rough Rider compressor by Audio Damage
Simple Delay by Blechturmstudios
Phasebug by Betabugs Audio
PhoneMon by Ralph Gonzalez
W1 Limiter by George Yohng