Pokémon Red and Blue/Viridian City

'Viridian City isn't exactly a bustling burg, but it's bigger than Pallet Town. There you'll see your first Pokémon Center, a place where you can go to restore your Pokémon to full health. You'll also see a Pokémon Mart, which stocks items useful to Pokémon trainers. This one has a delivery service and will need your help to make a special delivery.'

A Parcel for Professor Oak
The Mart in Virdian City is the second building from the bottom. The manager inside won't sell you anything at this point, but he will give you a package to deliver to Professor Oak.

When you bring it to him, the Prof. will give you a Pokédex, a sort of digital encyclopaedia with entries for every Pokémon--as soon as you fill then in.

Before you skip town again, head to Gary's house in the Northeast and get the Town Map from his disobediant sister.

Seeing the sights
The first building from the bottom is the Pokémon Center. These centers will heal all of your Pokémon for free, and you can use their computers to access your item storage and change your Pokémon roster. Get in the habit of going here first whenever you enter a new town: you don't want to be unprepared for any of your rival's sudden challenges.

The third building from the bottom is the Pokémon School, where you can acquire some good tips from the blackboard. There is a potion hidden behind the weird tree in the northwest corner of town. But you can't go any further north; a sleeping man is blocking your way and won't move till you've made your delivery to Professor Oak.

Load up on Poké Balls
Once you've completed your errand, return to Viridian City and hit the Poké Mart a second time. They'll sell you whatever you need now, and you'd be wise to stock up: since you lose half of your money when you run out of usable Pokémon (because they've all Fainted, for example), it doesn't pay to keep a lot of cash on hand.

Buy as many Poké Balls as you can afford (you'll be needing them), some Potions if you're running low (they're only for sale here in the Yellow version) and maybe an Antidote or two to play it safe, since there are plenty of enemies that can poison your Pokémon in the Viridian Forest.

Where to Next?
If you head north, you'll find that the old man who was blocking your path has finally gotten himself together and out of your way. If you ask for a lesson in using Poké Balls, he'll be happy to oblige (although you won't get a choice in the matter in the Yellow version). Once that's over with, you can head past him to Viridian Forest, the area you'll have to cross to get to your next destination.

But don't be too hasty! Route #1 was full of Pokémon that you can catch anywhere, but the area West of here, Route #22, has a few interesting finds, especially in Yellow. But don't go past the grassy area, or your rival might challenge you to a fight when you're not quite ready.

Using Poké Balls effectively
You'll need a bunch of good Pokémon before you challenge the Viridian Forest, so spend the next few minutes tracking them down.

Whether you're trying to catch all of the Pokémon you see, or just the ones that you need, you should always be prepared for a chance encounter with a rare Pokémon. This means having at least 3 or 4 Poké Balls on you at all times, and at least one low level Pokémon of your own.

The last part is important, since it's incredibly difficult to catch Pokémon when they're at full strength. They're a lot easier to catch when they're in the yellow damage zone, and a cinch when they're in the red, but you'll need a weak fighter to take them down to that level or you may accidentally knockout your target as you whittle away at its health. Sleep, Paralysis, and other negative conditions also make catching wild Pokémon easier.

Leveling up your Pokémon
Pokémon need lots of EXP to level up, so weak Pokémon who can't survive battles to get the EXP at the end can be hard to level-up unless you use this little trick.

Simply put your weakest Pokémon at the top of your roster, and then swap him out for a tougher one at the beginning of every fight. The new Pokémon will do all the work, but since every Pokémon who appeared in the fight gets to share the EXP, the weakling will still get half! But beware: Since you're using your first turn to switch Pokémon, your opponent will get the first attack.