Its a bit pricey but, from what i undertsand sway bars, strut bars, and new bushes, are your best bet. Followed by struts and springs, to lower the centre of gravity..[but dont go slammed cos that'll just back step all your$$ spent on other upgrades]
and then lastly tyres are the biggest concern...you can spend thousands on your setup, but throw shit tyres on and you'll eat the wall...
but im not an expert on this, far from it...but thats what i understand from the suspension/handling side of things...