As the newbie to the forum, but NOT to Mustangs (i.e., Fox, SN95 & S197) I will throw my .02 cents.
You cannot go wrong with a good set of quality struts and shocks (i.e., Bilstein, Tokicos, Ford Racing, etc.) Dont forget to upgrade with GT500 upper strut mounts and some camber bolts (depends on if you lower or not)
On the coil springs, the debate (not starting one) of progressive and linear rates always seems to get people talking... I suggest looking how low do you want to go 1"- 3"+/- drop etc. Also, buy quality name brand stuff which has been proven to perform as expected.
Control arms, braces and sway bars are all good too, but as with everything in life... How much can you afford $$$ Some of these packages can get expensive and then you sacrifice ride quality.
In the end, its your car... do what you like and take into consideration what you intend on doing with it (Commute, cruise, race, track, drag, etc.).
Either way, enjoy your Pony!