Strongly Fancied System uses the Mirror newspaper look for any Non-Handicap race of up to seven runners, where the horses marked (SF) or (F) are not first or second in the betting forecast but are quoted at 10/1 or under.

In other words pick out the horses that have the strongly fancied or fancied letters against them that are neither favourite nor second favourite and are not over10/1 in the betting forecast.

If this leaves you with more than one race, reduce to one as follows;

If you have a choice, then take a flat race in preference to a jump race.
If still more than one race, take the race with the smallest field.
If still more than one, then take the one with the highest prize money.
If still equal, take the race with the highest priced forecast favourites.

The selection is the (SF) horse that you are left with.