There are many methods you can use but one of the fastest and least expensive may be a fine to medium wire wheel on a 4 -4.5 inch grinder. A light touch and you get down to bare metal very quickly. Wire wheels are about $15.00 at Sears Hardware and others. Wear a mask, gloves, ear protection and face shield. Do not use an ultra stiff wheel or it will remove more than paint. This will leave a good surface profile for your primer to adhere to. Other methods include chemical strippers (messy and $$), sand blasting (slow and messy), or sanding with a dual action sander (slow). Good Luck
In reply to MartinSR - there is no "problem" (worn out clique) in Houston or anywhere else when using the wire wheel method on old paint.
If you get agressive with it you may cause damage but if you use the "light touch" the old paint will come right off with no heat build up or metal damage. If the paint is new then other methods might work better.
