With the wide range or play activities and tools needed for them, you can be sure that you will have at least one full bag of items. Yes submissives, you need to have your own play bag also.
I can hear it now though. Dominants use the toys, why do I need to have some? Well here's the scoop. A lot of the toys used on us are not easy or impossible to clean from person to person. These toys should be one person only. In those cases, you definitely should respect your Dominant by bringing your own.
It used to be that Dominants would ask you to have certain things on hand before you played with them. Rayne and I both think that Dominants are getting lazy in this aspect. Submissives should always have some toys on hand when playing in a casual relationship.
It goes without saying that submissives should bring their own insertables. Dildos, vibrators and anal toys should never be shared (unless they can be boiled clean in between, and only a few materials can do that). Gags must be paired with one person also. Blindfolds might also be something you consider for personal use.
If you are into rope bondage, the crotch rope is typically a separate piece of rope and belongs to the bottom, so having your own will save your Top having to give away his rope. It's also nice to have your own cuffs and play collar (if you aren't collared).
Always have safe sex barriers and gloves with you and your preferred lube so that you don't have bad reactions during play. If you have a latex allergy this is important to carry your own non-latex gloves and condoms. Also, if you like flavored lubes, or want to give a blowjob, bring flavored condoms. Safety is everyone's responsibility.
Lastly, when you have a specific activity that you enjoy, make sure you bring your favorite and unique toys. Sometimes the Dominant just doesn't have a lot of toys that you enjoy in their bag. Having some that you know you like will make for more enjoyable play.
Make play relaxing and enjoyable. Both of you bring a toy bag. The options will open up a whole new world.