I say this every year but Fall is my favorite season by far.  
The crisp air, the changing leaves, apple cider, and the awesome outfit combinations you can achieve with layering.  
This jumpsuit (last worn here) is perfect for summer with its light breezy material and thin straps but can also transition along with the season.  
jumpsuit-wedges-casual-style-dc-ootd-blogger
jumpsuit: anthropologie (last worn here) | jacket: zara (identical & under $50!) 
booties: tory burch via nordstrom rack | necklace: loft | bag: coach | sunglasses: rayban

Since it is still earlier in the season, the exposed legs of the outfit haven't made it unbearable to wear for slightly colder days. 
This leather jacket I snagged from Zara a few years ago is still a great piece that adds the warmer and a slight edge to the whole look.  
This one is basically identical and such a good deal.
jumpsuit-wedges-casual-style-dc-ootd-blogger
jumpsuit-wedges-casual-style-dc-ootd-blogger
Adding a third piece to my outfits has become a staple and really a default in terms of deciding an outfit.  
In warmer weather, I find myself with "nothing to wear" because I like to buy jackets, blazers, etc. because I really feel that a great third layering piece can really elevate any outfit and gives you more outfit options.  
jumpsuit-wedges-casual-style-dc-ootd-blogger
jumpsuit-wedges-casual-style-dc-ootd-blogger
If you are looking to add or expand your fall outerwear choices I would highly recommend starting with a good black blazer and black leather jacket (or faux like the one I'm wearing)!  
I would suggest investing a little more in these items because you will wear them often.  
You want to ensure better quality so you don't find yourself buy a new blazer or jacket every year because you end up spending more in the long run.
jumpsuit-wedges-casual-style-dc-ootd-blogger
jumpsuit-wedges-casual-style-dc-ootd-blogger
jumpsuitanthropologie (last worn here) | jacketzara (identical & under $50!) 
bootiestory burch via nordstrom rack | necklace: loft | bagcoach | sunglassesrayban

And I just wanted to point out these booties quickly.  These may have been one of the best sales I have ever found.  I purchased these Tory Burch booties at Nordstrom Rack about 2/3 years for around $60.  Yep. The best deal ever.  I don't wear them too often but I have already found myself grabbing for them multiple times this year.

Shop similar pieces below: