The main things to remember to bring are:

• The correct clothing. You don't need a fancy suit to do Aikido. All you need is loose fitting clothing such as a Tee-shirt and jogging pants. If you have a suit from any other martial art, then wear that.
  
  

• Bottled water.
  
  

• Any necessary medications. For example, asthma inhalers.
  
  

• Bring some light footwear for use between the changing rooms and the mat.