Dealing with potential damp issues over winter

We are new to caravanning this year and this is our first winter. We have a Bailey Autograph 745 motorhome. We want to know what can be done to keep damp to a minimum and how others deal, particularly with storage bedding etc. which would be susceptible to damp.  We are minded to seal everthing in vacuum sealed bags and leave in the van rather than store these things indoors.  Any general tips would be appreciated.  Thank you.