Aiming takes practice. When a little boy starts urinating in a standing position, be prepared to wipe up (and/or have him wipe up) around the toilet.
• Show the boy how to point his penis down to avoid spraying the room whether by sitting down or standing up. (If a little girl wants to urinate standing up, explain it doesn’t work but let her try anyway if she wants to.)
• Teach the boy to aim accurately by having him "sink the battleship." Float the corner of the envelope or a piece of toilet paper in the toilet and have him aim at it. (Cheerios, we hear, are also popular for target practice!)
• Or drain the water from the toilet bowl and paint a red target with fingernail polish on the porcelain toward the back. Or use a red grease pencil.
• Urinating into the "blue" toilet bowel water will turn it green. (This works with girls, to, but it’s harder to see.)
• In the summertime, and in the privacy of a backyard or woods, let a boy practice his aim.
• Let fathers and sons have a "peeing party."
• In the winter let a boy "write in the snow."
• If a little boy wants to stand but needs to be a bit taller, stand behind him and let him stand on your feet.
• Be sure the toilet seat can't fall down on a young boy in these early stages. Have your child check to be sure that the seat is up securely before he urinates.
• Start teaching your son NOW that the toilet rim needs to be placed down after he's finished.
Excerpted from Toilet Training: A Practical Guide to Daytime and Nighttime Training