For Dungeon Masters
Filling the role as Dungeon Master is not always an easy task, especially in D&D 3.5. Combat has many pitfalls for a new DM, you will need to be well organized and prepared to keep your combat on track. It is typically the DMs responsibility to track the initative, HP and status of the NPC's and know their spells/abilities and inventory, as well as any tactics they would use during the fight. I personally like to use traps and skill challenges during combat to give the PC's an advantage.
Skill Challenges - Dungeons and Dragons 3.5 has a broad set of skills that were often under used by Dungeon Masters. In fourth edition D & D Skill Challenges became much more popular and used combinations and sequences of skills to really challenge the players. Real life has consequences for failure and so should skill challenges for players that are untrained or perform poorly. A typical Skill Challenge has a set DC, if the PC(s) attempting the challenge fail by 5 points or greater, there is usually a consequence, if they fail by 10 points, the consequences are usually even worse!
Colored pipe cleaners: These can be used for AOE spells or distinguishing NPC's when you have multiple miniatures of the same type, like a gang of orcs.
Maps: There are some great map resources out there, most are printed by Wizards of the Coast or Pathfinder. Vinyl mats with a grid can be used as well and work fairly well for encounters you dont have a good map for.
Here's a couple places to start hunting for maps:
Players need far fewer resources than a Dungeon Master. The Players need little more than dice and a character sheet. It's helpful to have an understanding of the rules that apply to your character, but most groups work through that in a couple sessions. If you are playing a caster, druid, mage, sorcerer or cleric you should prepare a cheat sheet for your spells or have a Player's Handbook ready to keep the game going smoothly.