In my opinion, the Basic Manual for the Fighting Fantasy RPG represents the state-of-the-art of simplicity and playability in a Role Playing Game.
I've always shunned the Advanced version, for I deem it unnecessarily complicated, with too many Abilities, too many Magical Spells and too many Character Classes hindering the real strength of the FF game which is its neatness.
After all, if one desires a more complex RPG he'd better look after other titles, were they new ones or OSR.
However, it must be said the rules provided in the Basic Manual are decidedly too meagre to ensue a lasting play. Four or five adventures are generally enough to spoil the game of any involvment, leaving the Players with Characters too similar to each other.
So, here you are a small set of additional, yet simple, rules which represents a slight improvement of the Basic Manual without putting too many irons in the fire.
The Storyteller should choose which ones to embed in his game from the following.