Tips

First of all, ALWAYS, ALWAYS, ALWAYS talk to the people you meet in cities, in caves, on the routes, etcetera, because they can give you some really important advice and items! As a matter of fact, in Pokemon White, I actually got my Panpour just from talking to someone!

That's how important talking to people really is!!!

Second, you should try to catch as many pokemon as you can that aren't the same pokemon you have or any of your pokemons' evolutions. That way, you will have all the information you need to to complete the pokedex for each pokemon you catch!

Also, you should try to place pokemon on your team that are of different types. Otherwise, your team won't do so well against pokemon types they are weak to. For example, if you have a team of all water pokemon, then chances are, you aren't going to do very well against a grass gym leader because water is weak against grass.

I hope these tips help!