So….
Town planning:

Make Dartmouth Road one way. This should flow into the town centre so that people stuck at the lights look at the shops and think 'I might pop in there' rather than gunning it as they flee the S Circ.
Do new pavements at the same time.
Good point re traffic islands made by another poster.
Sell off a bit of the Perry Vale car park and develop (I'll get back to this - there are challenges re access). Use funds to:
Pedestrianise the Perry Vale triangle by EJ Carpets.
Make Perry Vale one way from the car park to the A205 (traffic flowing into the South Circular again)
Build a new, modern (fit for purpose) railway station building.
Transfer the cab company into this building which stops cabs waiting and causing traffic issues on PV.
Encourage Wetherspoons to do up the frontage of the Capitol - there are trees growing out of it for goodness sake.

Transport:

Get two more ELL trains in rush hour going through as a priority.
Support additional train/ overground capacity at other stations in the borough which will alleviate the FH/HOP line - 4 trains an hour through Crofton Park as a priority. Additional capacity through Catford Bridge & Lower Sydenham as well.

Broaden offering so that additional footfall at weekend and evenings:

V22 at Louise House - engage to have events/ access at the weekends to drive footfall along Dartmouth Road.
Cinema - build a new, purpose built cinema - at PV car park.
Broaden the restaurant offering - I'm imagining small and quirky - somewhere to go before going into town, or to pop in on a work night - Japanese would be welcome; something like Banana Tree Canteen maybe and I would love a decent burger offering.
A number of shops could then open later at night to meet demand of those coming home from work - that is a big difference between here and other parts of London.

Shops (some mentioned already):

General DIY store (like Sydenham DIY)
Beauty parlour (like Neroli) - they always have nice interiors and stay open later so add to evening offering.
Picture framer (the guy in HOP retired, so a gap there)
Health food store
Launderette
Decent wine shop/off licence
Kid's clothing store I think could work here.
I'd love a women's clothing store - somewhere 30-40 yr old women who work could go to get work clothes without ever having to go into a Shopping Mall or Oxford Street - but not sure it would survive here yet. I don't think a man's one would!
Another charity shop - bear with me - that is solely for books (I'd like a bookshop, but I don't think it would survive).
Greengrocer

There's a few thoughts for now!