The basic strategy to prolong erection and postpone ejaculation is to make the penis less sensitive to physical stimulation. Less sensation means it takes longer to reach the point of orgasm.
This is mostly accomplished by getting used to the sensation through practicing more sex to gain stamina and become less responsive to sexual impulses.
Using male enhancement products that contain special chemicals which make the penis less sensitive in order to last longer (usually anesthetics or similar) in forms of sprays, ointments, lotions, creams, pills, etc., or special condoms coated with these substances, turn out to be quite a helpful option, but it is not advisable to use too much, as one can lose his erection and it can also diminish the sensibility of the sexual partner.
There are also some prescription drugs available for this, but they have to be prescribed by the physician. Side effects of other drugs (like anti-depressants) can also sometimes cause reduced sensitivity, but more commonly they cause erectile dysfunction. There is also a method of injecting vasodilator (drug that widens blood vessels) directly into the penis.
Special penis exercises as “the squeezing technique”, where the tip of the penis is squeezed just before the orgasm, are not very effective, as it is hard to catch the right moment. Other similar self-applied methods, as pacing strategy or “start and stop technique” (trying to delay orgasm by stopping just prior to it), and testicular restraint (restraining the testicles from moving during sex which in theory delays the ejaculation) can become helpful with practice. Another self applied technique is to reach an orgasm (usually by masturbation) prior to sexual intercourse and then the second orgasm (achieved during sex) will take longer to reach.
The best way to address the problem is combining self applied methods with chemical substance treatments.