I have played RPGs since 1981 with a preference for science-fiction RPGs. The first games I started with were playing and running STAR FRONTIERS and CYBERPUNK 2.0.2.0 (R.Talsorian Games), RINGWORLD (Chaosium Inc. games) and boxed (BECMI or Cyclopedia) DUNGEONS & DRAGONS. I also play and run FATE CORE, and will soon run TRAVELLER (Mongoose Publishing's 2nd edition)!
My special GM skill is Powers of Description. I will describe science-fiction verisimilitude; you will believe you are there. I also try to tailor the game to each player's preferences: combat, role-playing, storytelling (complex story-arcs), political intrigue (if you're too involved with NPCs, they might make you a leader!), whatever.