You can get follower sets and enhancements from follower missions, but they don't appear often, so probably the fastest ways to get them are:
1) Build Level 2 Dwarven Bunker / War Mill lvl 2
Get War Mill Shipment from Work Orders
2) Build Level 2 Salvage Yard lvl 2
Get Crate of Salvage from follower missions (there is a chance to get them from every mission)
Open them in Salvage Yard
Here is a short video-guide: