I'm not sure I'd go rushing to introduce bold colours like orange, navy etc with such a cool and sparkly grey/silver.
My big takeaways without changing/spending a crazy amount are to change the silver wall to something much lighter and matt. Blush/dusky pink is very in at the moment and pairs well with grey/ silver. I'd choose quite a pale shade and make sure it's not too 'girly' pink 
It would bring it right up to date and warm things up a bit - also toning well with your darker grey woodwork and orange door.
At the moment the silver wall is far too similar to your carpet and almost looks like an extension of the carpet (from a distance!).
My next thought is to change the sofa layout and TV. Is there any chance of mounting the TV where the mirror is and having your mirror over the mantle? Try hanging the mirror vertically over the fireplace which draws the eye upwards/ gives the feeling of higher ceilings. You might require a bigger mirror for this or plainer framed one.
I'm picturing the sofa facing the mirror wall- is there a window where you're positioned taking the photo? And the armchair on the wall where the display unit is.
I like the idea of houseplants (also very in at the moment!). I admit I've cheated in my living room and used plastic plants 
I'm a decent gardener but I'm crap at remembering to water things indoors.
B&M have quite a nice selection of homewares right now if you can find a well stocked one. I'm wondering if you can mix rose gold/copper with grey and blush pink. They have a lot of blush and copper accessories. I think it would work if the silver-sparkle is toned down a bit.
Sainsburys homewares are also really nice albeit a bit more expensive. I haven't checked this season's offerings but they're usually very on trend and look more expensive!