Stimulation of the prostate gland can often cause an increase in the pleasure caused by stimulation by the penis. Prostate stimulation is usually easiest and safe if done using a gloved hand, exerting mild pressure against the forward wall of the anus. The prostate gland is typically easily palpable, and feels like a gentle dome. One should listen to the feedback of one's partner when finding the prostate gland, as its location can vary from person to person.
2.2. Use of Sufficient Lubricant
Most penetrative sex or manual stimulation feels better for both parties when sufficient lubricant is used. Lubricants also assist the efficacy rate of barriers. Water-based lubes are the most versatile.
Nonoxynol-9 has been proven to kill the HIV virus in a test tube. Don't use nonoxynol-9 by itself! That won't do any good. There is also the chance of an allergic reaction to nonoxynol-9. Before using it in an intercourse, do a test on a small patch of skin. If there is any irritation don't use nonoxynol-9.
2.3. Deep Breathing
Breathing rhythmically and deeply before and during sex can increase pleasure. Elements of atmosphere and ritual, such as turning off the telephone, putting good music on the CD player (on repeat play), engaging in rhythmic touching/caressing, keeping protracted eye contact, and lighting candles, are also helpful.
2.4. PC Muscle Contraction
Contraction of a muscle called the PC (Pubococcygeus) muscle can increase sexual pleasure. This muscle may be located when urinating, by noticing what muscle you contract to stop the flow of urine. This is the PC muscle, and it may be exercised by contracting it repeatedly and rhythmically, or by contracting/inhaling and relaxing/exhaling. It may be used during sex by contracting it when close to orgasm.
2.5. Good Communication
There isn't a substitute for being able to tell your partner during sex when something doesn't feel good, or when it does. There isn't a substitute for actually asking for what you want, and for learning over time what your partner likes. Communication on sexual matters will tend to increase both the pleasure and the safety of all involved. Furthermore, knowledge of your partner's fantasies will allow you to construct verbal/theatrical fantasies and hot talk during sex to heighten pleasure.
For consensual sex, partners must respect each others' requests to slow down, back off, or stop. If you feel that your partner would not listen at your request to stop doing something to you, you might consider whether any sex with him is really "safe."