Acne can make shaving difficult (and sometimes painful.) Take extra care when shaving. Don’t shave the tops of pimples off, if you can help it. And try to shave super carefully over acne blemishes.
If your blade razor is irritating your skin, try an electric to see if that helps. If you have more serious inflammatory acne, or if shaving in itself seems to really irritate your acne, you might want to experiment with a beard trimmer. This will clip the hair short but not completely remove it, and it can help save your skin from irritation (at least until acne starts to clear.)
Just FYI, sometimes what men think is acne is actually folliculitis, or an inflammation of the hair follicle. Guys with curly hair in the beard area are more prone to folliculitis, because the hair tends to curl under the skin. Again, leaving the hair a bit longer can help.
Not sure if it’s acne or folliculitis? Your doctor can diagnose folliculitis, and prescribe medication if you need it.