1. Create a main character.Let's say, Oh, Luke Skywalker. An orphaned country
Most of the people who read your book will be unconfident males. So make your main character a Loser. Aimless, shy, cowardly, guilty, ill, lazy, rural - any of these will do.
2. Create a Quest.Become a Jedi, Deathstar Destruction, check.
Out of the blue, the Loser must be suddenly told that the fate of the whole world – or some other world - rests in his incompetent hands. To save the world he must perform some task, confront some nameless foe, learn some mysterious skill etc.
3. Create a Motley Bunch of Companions.Wookie, Rogue, Comedy-duo Robots, Check.
The Loser/Hero must have a Motley Bunch of Companions drawn from different human species e.g. dwarf, elf, Rotarian etc. Each of these companions will have one particular skill such as sword fighting, lasso twirling etc which will come in handy at a particular part of the story.
4. Create a Wise but Useless Guide."Help me, Obi-Wan Kenobe, you're my only hope.". Check.
The Guide is wise adviser who knows all about the Quest, but never fully reveals it. He also appears to have immense powers but will not use them when they are most required.
5. Create the LandAgrculture on a Desert Planet. Check....
The first thing the Motley Bunch must do is travel some phenomenal distance through an assortment of vastly different terrains and climates. All Fantasy Lands have every conceivable form of climate and landform - mountains, deserts, swamps, glaciers, forests - arranged randomly across the landscape contrary to any known principles of geography or ecology.
6. Create the EnemyCalling Darth Vader! Call for Mr Vader! ...and so on. Hey, the System Works!
Every Fantasy Land has a Dark Enemy, an almost omnipotent ArchVillain who is trying to utterly destroy it....