Premature ejaculation can be psychological predominantly. Follow following techniques for improving retention. 1. Practice to increase the duration of retention by masturbation. 2. During sex use woman and top position and don't flex your buttocks much. 3. During sex don't thrust rapidly which increases the risk of premature ejaculation. 4. When you realise you are going to ejaculate try distracting your mind by thinking completely different issue. 5. Use thick condoms which reduce the sensitivity. 6. And finally when all above measure don't work u can apply creams like dolocaine ointment which will reduce the sensitivity of penis. Hope this helps . Be happy