So here it goes.
Your immediate action, and for the following 72 hours, on an acute injury is to reduce the amount of blood that is going to travel to the site of injury. This can be accomplished with the use of Ice, Compression and Elevation, NOT HEAT!
ICE constricts the blood vessels so can substantially reduce the amount of blood flow to the area.
Ice every hour - I often use a single ice cube and move it over the site until completely melted. The key is to get the area as cold as quick as possible, some of the off the shelf ice packs can be pretty useless!
If you'd rather not get a cold hand as well, simply get a load of ice and place in a wet tea towel. Beware of frost-bite if you just leave ice in contact with the skin, a light application of oil to the area can prevent this.
In between icing place a Tubi-grip over the area. You want it pretty tight, so double over if necessary. Tubi-grips are sold at most high street pharmacies and come in a range of different sizes. These aren't the knee bandages you see many people wearing during exercise!
Tubi grip can be worn all day and all night if necessary.
Simply try to keep the injured area elevated above the heart - a simple way to reduce blood accumulation.
These are a good idea - IF NOT ALLERGIC, check with Dr if not sure. They can be taken orally or used as a gel.
Once the 72 hours is up you generally want to start increasing blood flow to the area to aid healing. The best way to do this is to dilate the local blood vessels with the use of HEAT.
Again, apply at regular intervals, every one to two hours if possible. This can be achieved with heat packs, hot water bottles or a hot/warm bowl of water.
At this stage I would also advise you continue to use the Tubi-grip, especially if the injury is to the knee, foot or hand.
These are general guidelines and work well for most acute minor injuries.
If you are in any doubt about your injury GO TO A & E.