Do not mix opiates and benzos it's extremely dangerous, and even people who are experienced with both drugs have overdosed and died from it.
If you want to take oxy and you have never taken it, take only 5mg of it and see how you react to it. Do not take more than 10mg of the oxy at once. Take the pills orally. Keep in mind that opiates can be extremely addictive.
I've never used any benzos recreationally so I have no idea about those but start on an extremely low dose, and do not combine the benzo, or opiate with any alcohol. If you take too many benzos you will black out.
Stay safe.