If your hair's healthy (no dryness issues) and you are ready for the upkeep, I say start with highlights. I use Schwarzkopf (for lightening dark hair) first, this gets my hair to a medium brown then I do a hard Aphogee treatment wait a week or two then use Superdrug hi-lights kit (with the cap and crotchet pin). This gives me a nice natural looking colour and it doesn't look weird growing out. I DC at least 2 hours every week and heat style (flat iron) 2ce a month.
I also BKT every 6-8 weeks and will soon be incorporating Cassia into my reggie, my hair's doing great and is very soft.