Do some reading at this site, lots of free information and will explain a lot on improving steering/suspension.
DazeCars, Ford Galaxie Mustang tech and restoration
Start with suspension 101, 1" UCA relocation (Shelby or Arning drop called often), roller spring perches, etc.
The UCA 1" drop will put your tires flatter on the ground giving better steering and road holding. The roller spring perches allow the suspension to move freely and adjust quicker to road changes, curves,etc. New UCA/LCA will help if your old ones are original/worn out. If a daily driver I'd follow what's above, new stock components with UCA 1" drop/ roller spring perches/ bracing/ 1" sway bar/ roller idler if manual steering, better gas shocks.
I also replaced my rear leaf springs with 4 1/2 mideyes and it put me level with 1" drop front springs. This made a huge difference on how the front reacted, no more 'pushing' when entering a freeway from an on ramp, used to waddle as the rear would sway and try to change the direction the front tires were pointed.
Jon