For 1-99, since when I returned I tried to get a friend to join as well so started a fresh character. Without using my old character to support it, was able to get to 99 in about a week avoiding Gusgen Mines GoV parties, and Abyssea pre-75.

I'd recommend starting in Bastok if doing a fresh run. For a few reasons, several GoV locations near town, easy town to get around in, decent enemy drops in the area as well. Beehive chips, Wild Onions for gil, and zinc ore to start working on Tenshodo fame early. Have done this route on multiple jobs, if have problems in some spots, upgrade your weapon and spells first as they will make the largest difference.

1-9 South Gustaberg: Do the worm, bee or goblin FoV pages, staring near the town exit at first, then going up on Vomp Hill around level 6ish and make sure to open any brown caskets you come across for chances at free level 9-10ish gear like the Scale armor set.

9-23 Dangruf Wadi: Do the goblin page till around 16 or 17, then jump to the leech/bunny page til about 22-23. Keep opening those brown caskets, they can have level 70ish gear in them which NPC for about 6-10k on average, and some of the crafting materials that show up are 20k+.

23-43 Korroloka Tunnel: Start with the bat/worm pages which can be a little rough starting out depending on job and what most of the enemies are checking as they would be a DC-T range starting out, they last till 33ish, when can swap to the Leech page that can get you to 43. Still keep at the caskets, more 70ish gear and crafting items, but also the Rare Brachyura Earring which can be AH'ed for about 100k(Price on Siren), or kept for later as its effect can be handy.

After 43, can stay in Korroloka for Gigas till 50, but better to go to Upper Delkfuts tower as the Gigas there are the same level range, and more numerous, just need to be careful of Elementals spawning. If going to Delkfuts, work on getting your nation missions done before heading there, as there is one that has you going to the same place.

50-57 Garlaige Citadel: The Beetle and Siege Bat page is your friend, if you can camp by the Banishing Gate, will need sneak/invis to get there if want to avoid agro. The tri-bats and skeletons agro sound, beetles agro Sight, and the Seige Bats do link. Can also stay near the entrance. For the mages, one key thing to do is Aspir the beetles to help reduce downtime.

After 57, there are lots of options but not all work well for every job, so have to find one that works well for your job. Try and keep to GoV page areas though for fastest leveling. Crawler's Nest, Boyahda Tree, Sea Serpent Groto, Bostaunieux Oubliette, Gustav Tunnel, Kuftal Tunnel, and Quicksand Caves are likely your best options.

Now if you happen to get to know someone who is willing to burn pages on BST for you, I highly recommend the Antica page in Quicksand caves and go in the Western Altepa J-9 entrance. Stay at the bottom of the entrance, while they pull the Antica, alternating between the South and North sides. The mobs are barely EP to a 99 so they die really quick and there are lots of them. It is not uncommon to complete 4-5 pages per pull, and can pull almost non-stop.