WHERE are you in mid levels... what road / street ?
If you are near the Western side... then take taxi down towards Pokfulam / Hill Road, and past the Traders Hotel.
When you hit T-junction, Hill Road / Des Voeux Road, there is a series of bus-stops, then catch any bus to the Western Harbour Crossing Toll Plaza (right beside ICC).
on your left, beside Tram terminus (opposite Kwan Yick Build Ph1), bus 904, 971
on your right, beside Pacific Plaza, bus 905
Bus crosses the harbour in 12 minutes max... usually only takes 5 mins