If you are interested in giving your painted furniture projects a patina of age, a good technique to master is antiquing with dark wax and/or glaze.
I am a very visual person and I learn from seeing people do things as well as closely inspecting furniture in antique french shops. Go to an expensive suburb and check out the French antique shops and really peruse how authentically aged pieces look so that you can replicate the look on your pieces if this is what you are after. I still have a long way to go in my learning and skills development but here are some pieces that I've used dark wax and glaze to "antique".
Here is a detailed tutorial on using ASCP (or other brand) dark wax.
Antiquing can be VERY scary the first time you do it. You stand there with the dark wax your brish and you are just so scared of messing up your pretty freshly applied paint. Maybe we all should have a quick vodka before we antique and distress and it might all be more relaxed and authentic. Perhaps it's just me. Anyway a good place to start and learn on is an ornate mirror. If you hate what you end up with you can paint over it, chuck it out or give it away to your auntie for Christmas!
This mirror below was just an inexpensive gold mirror that I picked up for $10 at Rozelle Markets. I painted it in a cream Porters Paints Eggshell paint and then used glaze to antique it. Here is my DIY recipe for glaze.
I would use a glaze when you don't want to use wax or are using a poly. While I love wax I wouldn't wax a piece that I know I'm going to repaint again. Only ASCP painted well over previously waxed pieces. If you aren't 100% sold on a colour then use another topcoat and wax to antique your pieces.
Here is the before photo of a dressing table my clients wanted me to paint and glaze.
And after but before hardware was added back on. The glazing has really brought out the detail of the oak and especially around the carvings.
This French chateaux chest of drawers are one of my favourite all time paint projects. I adore them. I used ASCP Paros Grey, ASCP Pure White and Dark wax.
Use dark wax and Off White paint to turn a damaged pine cabinet from this...
to this (although I also loved it stark white above!)