Switch it up! Don't just have the same old "Oral, oral, PIV" sex. Have some petting then some oral, then a little PIV, then STOP and go back to oral, then to petting again, then to manual stimulation, then back to oral for one then the other, then a little PIV, then back to some oral and... so on.
My Man can last for hours this way. Just don't have straight PIV as the "main event" and then that's it. Some men come too quickly if that is all that is done. Switch it up. It works, well.