Don't raise or lower it first off, just go take it to a track, Grand Valley Speedway is a good tuning track for starters. Drive it around a bit, notice the way the turns and grips the corner. If it rolls too much and has a soft feel and easily pulls along the inside of the corners then bump the spring rate gradually and retest. If the stock spring rates are 4.0 front and 3.0 rear, then keep the ratio 4:3 as close to possible. When the car starts to go wide in the corners or loses grip and slides, skid smoke, etc. You have probably reached the threshold of maximum grip from spring rate. Bump it back down to the next setting that won't lose grip. Depends on the tires you are using to tune also, I try to start with the lowest grade tire I can maintain control of the car with. When the spring rate is set, you can switch up a tire grade and start higher speed runs and start tuning the feel of dampers and anti-roll bars. Formulas and shortcuts aren't good substitutes for good old fashioned trial and error.
