One of the most vital things to remember when selecting paint colours is how they will look with the fixed elements in the room. Choose what appeals to you but, if you don't plan to change the finish on your hardwood floors, cabinets, trim or furniture, you do have limits. Depending on the style and cut, medium oak wood is generally found in traditional, modern and contemporary settings, and its warm tones call for a certain palette.
From dusty, neutral grey/beige to rich sages, greens with brown undertones are a natural choice to pair with your medium oak woodwork. Your choice is also influenced by the style you're hoping to reflect. Clean, modern schemes are more likely to use neutrals, like a light green with beige or grey tones. Contemporary looks might choose a sage shade and traditional rooms might use a deep mossy green. Avoid anything too yellow or bright bluish-greens.
With oak on your cabinets, floors or trim, deep wines, berries and creamy Spanish tones of red will continue the warmth coming from the honey hues in your woodwork. In the case of oak cabinets, furniture and floors, red colours on your walls also work well with white trim. When choosing your red, ensure it isn't too orange, or it will clash with some of the tones in your oak. Terracottas and brick reds work if they have enough pink in them, but stay away from anything too rusty.
Warm neutrals, like ivory, beige, light gold and brownish grey, also work with medium oak. Using all neutrals (particularly grey) gives a very clean, contemporary or modern result, whereas using them in combination with greens or reds keeps in the traditional vein. A good way to choose your colour is to take a sample of wood stained and lacquered to match your woodwork with you to the paint or home improvement shop so you can hold your swatches up to the wood sample and ensure your colours don't clash.