Welcome to the GM Forums Robyn!
Some of the basics I'd do if they have not been done would be things like changing the fuel filter, transmission fluid, and power steering fluid.
Inspect things like ball joints, engine/transmission mounts, control arm bushings, etc.
Consider replacing struts if they have never been replaced, if you replace any of those things, or if the car has not had a 4-wheel alignment done recently, then having one done would be good to do.
Do you have a supercharged motor, or the naturally aspirated one?
Either way I'd highly recommend getting the lower intake gasket replaced with the Fel-PRO aluminum lower intake manifold gasket, the old nylon one that is on there is known to fail, and that can possibly lead to catastrophic engine failure.
Both motors will have the same lower intake manifold gasket, so if you ever tackle the job and need parts numbers let me know.
The plastic coolant elbows are known to get brittle and break, they make some aluminum coolant elbows now that are a better replacement elbow, again if you need part numbers let me know.
I am sure I forgot to mention something, I'll check my post again after I get some sleep.
2006 Pontiac Grand Prix GT with SC
1996 Buick Park Ave NA