Of course, when I was going for 99, I mainly focused on trees (with herb runs added in) because they're the best xp wise.
Once per-day I would do the following:
Tree patches: Lumbridge, Fally, Taverley, Varrock, Gnome Stronghold
Fruit Patches: Catherby, Gnome Stronghold, Tree Gnome Village, Brimhaven (You could additionally use the teleport crystal and do the one in the elve village if you have completed rolving elves).
Special trees: Calquat near that Thai Bwa Village thing.
Every third-day I would do the Mahogany trees on Fossil Island.
I didn't do the most efficient route but I'm sure you could find a comprehensive youtube guide that outlined the quickest pathways depending on what teleports you have available.
Then I would do a few herb runs a day (probs 5/6 a day now that mobile is available). Patches include: Fally, Trollheim, Zeah (via the Xeric's talisman), Catherby, Ardy and Canifis (via Ecto). If you've done Rum Deal, you can also use the teleport to get to Harmony Island but that wasn't available for me.
When I was hunting the pet, I'd also through in Seaweed Spores, Mushrooms and Cactus (I'd do like 5 seaweed runs per day alongside herb runs as they have the best drop rate of pet 7500/1 and take 40 minutes to grow).
Not a hugely comprehensive answer but the routes/xp rates etc can be youtube'd and it depends on what you have access to on your account.