So, step 1 is to change the wheels and tires. Check an online tire calculator. You might not want to put 30" wheels on a car that could barely handle 18" size. When changing the alloys, there are a few essential things: diameter, offset, and wheel width. When combining these, the end result should be a better-handling vehicle. Go for the lightest alloys you can get. A heavy wheel will require more torque to spin and longer stopping distances. Also, at this step, you may go for some spacers, but be careful to not push the wheels outside the wheel-arch and secondly, if you install thicker than 5 mm (0.2") spacers, use longer lug-nuts.
Choosing the correct setup for a suspension might be a tricky part. I would go for an adjustable coil-over kit, which will allow you to stiffen or loosen the suspension travel and the bound and rebound rate. However, don't even think that stiffer always means better. If the car is too stiff, it will bounce, and you'll lose traction on the next bump on the road. Also, if you use the vehicle on regular streets, you might not want to feel every crack in the blacktop and every dime lost on the road.
We're not done with the suspension. Adding a camber kit might be a good idea if you are running the car on tracks. If you are just using it on regular roads, that will be primarily for a bragging subject at a car meet. As long as you have the right wheels and a decent coilover suspension, you won't need it. What you can do, though, is to put a strut bar between the car's strut towers. This will stiffen your ride and make it handle better during high-speed cornering. It is something you can do in your garage. Just order the right parts, and they'll fit like a glove. But remember: install it with your car on jack stands, not with the wheels on the ground. Better of, remove the wheels.
We're not done with the suspension yet. After changing wheels and tires and placing a new coil-over kit on the car, there is something else you can do: install a different torsion bar. This piece helps the vehicle in the corners to not lean too much. Basically, if the outer suspension is compressed, it will transfer some pressure to the inner side. Thus, the car will lean (or roll) less. But installing the most rigid anti-roll bar is not a good idea. That might work on completely smooth tarmac, which everybody knows you can't find on regular roads.
On off-road cars, those anti-roll bars are often completely eliminated. That will give more suspension travel and thus better grip. For a street vehicle, that's not a good idea either since the vehicle will lean too much on the outside due to lateral g-forces and might lead to an unpleasant ride and dangerous situations.