Cold-hardy material will now be dormant and should be put away for the winter. The two factors to keep in mind are that you want stable, cool temperatures, and protection from extreme cold. Dormant plants do not need light. Plants that are protected from extreme cold can be wired while the leaves are off. Keep an eye on the soil during this time. While your bonsai will be using far less water than they do when the leaves are out, the roots will continue growing and they do need access to water.
Your tropicals will also be slowing (or stopping) their growth. The biggest limiting factor this time of year is access to light. Make sure not to let them dry for more than a day or so between waterings. Also keep an eye out for insects. Indoors your plants are under stress, making them more susceptible to attack. Additionally, there's a lack of beneficial insects to keep the harmful ones in-check.
If your trees aren't actively putting out new growth you can stop fertilizing until the buds begin to swell.
As always, if you have any questions we're happy to help!