Size - Size of enemy force. When reporting, simplify when possible. For example, if you see roughly 20 soliders, call it in as a platoon. Vehicles should usually be identified, if you aren't comfortable ID'ing them, at least include what type, eg. Main Battle Tank, Armored Personnell Carrier, etc.
Activity - What the enemy is/was doing. Important information here includes posture, (relaxed, agressive, defensive etc.) movement speed and direction (if stationary, include the general direction the unit is facing) and actual activity (emplacing IED's, fortifying positions, manning a checkpoint etc.).
Location - Location of the enemy. Calling in grid coordinates is preferrable for this. If time is exteremly tight, use landmarks or your position to call the contact in, eg. North 1km from my position.
Unit/Uniform - Not as important ingame. Generally, you should just simplify this. If you know you are fighting Russian troops in the woods, uniform is going to be Russian woodland fatigues. Any important information for High Value Targets (HVT) can also be passed up here. For example, in a mission where you are trying to locate a HVT wearing gold sunglasses, informing higher that you have a enemy combatant seen wearing glasses would be important.
Time - When the enemy contact was observed, in game time. The O key is the default to bring up the ingame watch. If observed for a period of time, include that span, eg. 1640 to 1645.
Equipment - Any weapons, equipment, etc that the enemy has on or near them. Important items to note are support weapons, anti-tank rockets, communications equipment, IEDs, or intellegence.
PIR (Priority Intellegence Requirements) - Many leaders will not include this in their SALUTE reports, but it is often the most critical element of the report. PIR is anything that a commander specifies is vital to the mission. A commander who is operating with a mounted element may specify that IEDs and Anti-tank weapons are PIR, as knowing the enemy's capabilities are critical to how he chooses to develop his plan of battle. If a leader fails to specify PIR, use initiative to determine what is most important that he knows. For example, if you are conducting air assault operations and you spot enemy with MANPADS, but the commander has failed to define the PIR for the operation, use the PIR section to report up the threat to friendly air assets.
The most important thing to keep in mind while writing up your SALUTE-P report is not to assume anything. If you see two men with scoped rifles, prone in the grass watching a road, do NOT call it in as a sniper team. You have no way of confirming that the enemy's intent is to use the weapons in a marksman role. Instead, call up only what you see and can confirm. For this example, you would call up a two man team, observing the road, armed with scoped weapons. The commander can interpret this information at his discretion.