It can be incredibly disappointing to select a beautiful shade of stain, only to stain your oak cabinets and find that the stain is too dark. However, before you crack out the sandpaper, try to lighten the stain. In the worst-case scenario, you'll have to sand the cabinets down and re-stain, but there are several alternative avenues to try first.
Buff the cabinets. If you just applied the stain, buffing as much as possible off the cabinets can minimise the damage. Use a clean, dry rag and firm pressure to remove as much excess stain as possible. Look at the cabinets in a good, bright light to determine if there has been any improvement.
Mix up a cleaning solution. If you have just stained the cabinets, there's probably not much built-up dirt and grime, but cleaning them immediately may lighten the stain slightly. In the spray bottle, combine hot water and three drops of washing-up liquid. Swirl to mix the liquid, but do not shake it.
Clean your cabinets. Spray the liquid on a cleaning rag -- not directly on the cabinet -- and wipe them down. Use firm pressure. As soon as you've finished, dry off the cabinets and inspect them again to see if you like the lightening effects.
Measure out the paint thinner. Wear gloves to keep it from getting on your hands. Put a little in a plastic tub or container to prevent huge spills.
Rub the paint thinner on to the cabinets. Use a cleaning rag to apply the thinner, then scrub it with a nylon abrasive pad. You should see the cabinet stain lighten significantly. When you've finished, wipe the cabinets down again to remove the thinner so it does not continue to work on the stain. If they are still too dark, sand them down and start again.
Work in a well-ventilated area.