Can you recommend a simple way to update my single wide mobile home?

Debbie...Do you want to update all of it? Maybe send picture of room you want to begin with so we can get some ideas.

Sometimes local Church Groups have what they call Local Missions where members of the Church can come help paint etc maybe some teens would like to help out- Make a phone call ….

paint is the Quickest way to update any room.. if you have dark Paneling you can get it cleaned good, then use primer coat then a coat of paint over the top. that will brighten the whole room especially a Hallway..also a new coat of paint -white or Ceiling White will brighten/freshen things up too.. keep watch for Lighting sales at local Stores ( Walmart, Lowes, Home Depot etc) to add a new Lamp or ceiling light or ceiling fixture. new curtains, Try a different style like "no valance",which cuts off the top of the windows..or lighter weight curtains like sheers or opaque ones. Get rid of throw rugs except near exit doors where you have boots or shoes.. Spray paint is a good way to update lamps and picture Frames or Vases, Remove the Shade and cover the socket so paint won't get down inside.. Spray with metallic paint like Silver or Pewter or Copper or a color you like to accent . etc for what ever look you are going for. A new lampshade in a different shape...

Another Way to update a room is to take down all the pictures, pack away knickknacks and other Stuff that sits around.. Which you will have to do anyways before getting the Walls cleaned.. Hope these ideas help.

Start with replacing all bulbs in light fixtures with LED lightbulbs.

If any light fixtures are so discoloured or worn out that you can not get them clean any more, then I would suggest replacing them with the new integrated LED fixtures that do not take any lightbulbs. The retail price of these fixtures has come down a great deal in the last couple of years.

Flush mount are suitable for low ceilings.

Yes agreed. Without seeing photos, I think white or light-colored paint is a great place to start.