Welcome to the digital world, new tamer!
Let's do the tutorial and grab all the new tamer rewards.

You can save the Hatch Backup unit on the Kunemon hatching tutorial, and you can save the Rider Wing from the riding tutorial, too. I reccomend you to get a mercenary Drimogemon egg and hatch it yourself, because the egg from the tutorial can only hatched as a 3/5. and Drimogemon egg has a higher success hatch rate so it's easy to get a 4/5 or even a 5/5 Drimogemon. Don't forget to open the new tamer Gift Box to receive useful gifts for your adventure.

Continue the quest available on Yokohama Village until you finish the 5 Dats Badge quest. Go to Dats, then go to Western Village through D-Terminal.

At Western Village, fight Impmon and Drimogemon, until your partner digimon is around level 16-20. Your digimon should be at Champion stage right now, and at level 16, it's F2 skill should be unlocked, so it will be strong enough to one hit kill the enemy. At this point, your tamer level should be more than 10, which means you got exp boosters from tamer level 10 reward. Don't use it yet.

Time to go into the Wilderness Area.
From Western Village, go right, and you'll arrive on Western Village Outskirts. Go right again, you'll arrive on the Wilderness Area.

Fight Stingmon and Renamon here.
Your Champion digimon F2 skill should make it easy to kill them.
You could use your 31 minutes exp booster here, and ask for people around here to party.
31 minutes later, your digimon should be at around level 29-33, and your tamer level around level 20.

You don't need to buy disks and foods because the are Chocolates from the Gift Box. Use it to heal your digimon and tamer, save your money.

Don't be lazy to pickup loot from enemy digimon, because you need that for money to go into the next phase.

After your digimon reach level 30+, it's time to move on from Wilderness Area.

You should go back to Dats Center after your digimon hit level 31.

Return all Cracked Digiegg and Digiegg (Except Digiegg that contains DATA) you picked up while leveling your digimon, and it should be more than 20M, which enough to go into the Village of the Beginning via D-Terminal.
If you have less than 20M, sell any mercenary digiegg you got (I'm pretty sure you'll have at least 3 eggs at this point) 5M or 10M each, or on the worst case scenario, you can politely ask someone to give you 20M for the train ticket..

On Village of the Beginning, go right, into Silver Lake.
Go to Woodmon area and check if your digimon F2 is strong enough to one hit kill the Woodmons.
If your digimon is not strong enough, you can fight rookie digimon like Kunemon, or even the baby one like Tsunomon.

Find party member, and use your exp booster. Your digimon will level up and reach Mega level in no time. Again, the Chocolates from the Gift Box is always there to help you if you're too lazy to buy disks and foods.

You will get few 4/5 digimon from the Gift Box, but I reccomend you to play with the starter digimon because it's easier to reach Burst Mode, you don't need to buy the expensive Burst Mode item, just do the quest.

When your digimon level hit 44, the quests on Silver Lake should be available.
Do all of them because they give huge exp. Kuwagamon and Lilymon boss quest is kinda tricky though. If you don't want to wait for them to spawn, just skip the quest.

After finishing almost every quest on Silver Lake, your digimon level should be around 50, and tamer level around 30.

Continue to the next map, Silent Forest, then finish the quests like you did at Silver Lake.
I skipped the boss monster quest (Devimon, Soulmon, Warumonzaemon), and the demimeramon plate quest, too. It's time consuming. The attribute quest could be skipped too, no problem.
Find party for the Ogremon quest, and the quest is bugged, only show "Kill 50 Ogremon", but you need to kill 50 Ogremon (Leader) and 15 Ogremon (Captain) to finish the quest.

After you finished the Ogremon quest, go to the next map, Lost Historic Site.
There are many quest here, the map itself is quite wide. Finish it like usual, skip the boss quest if they're not spawned yet.

When you reached the end of the quest here (Quest from Tentomon), your digimon should be around level 70, and tamer level 40. And your money will be around 300-500M if you're spending it properly. And if you're lucky, you could get Exchange Tamer item which valued around 5T, woot.

You can go to the next map, File Island Waterfront now, but the quests won't be available until your digimon is at least level 74. This part would be really boring if your digimon is still below level 74 and you're out of exp booster or have no party.
You can level up on Lost Historic Site by fighting Dokugumon and Waspmon, usually there are a lot of people party there, or at File Island Waterfront, fighting Arachnemon.

As soon as your digimon hit level 74, do the quests on File Island Waterfront, and boom-- Your tamer level is 50, and you got neat rewards like random 5/5 jogress digimon egg!

And that's the end of this guide.
I might update it on the future. If you have better place to level, let me know!
Thanks for coming!