One of the key factors in winning a game is how you play your opening hand. If you play it efficiently your most likely going to get a nice jump on your opponent, but if you don't play it right, you allow your opponent the starting advantage. So exactly how do you play your opening hand? Just follow these rules and you'll be fine.
 
1. HOW MANY POKEMON TO PUT DOWN: It's always an important factor in how many pokemon you bench. Most of the time it's bad to play all of your pokemon because your opponent can take advantage of you not being able to power up ALL of your pokemon and GOW out an energy less one for an easy KO. The only situations you should play all of your basics is if you your playing a stall and if you only drew 1-2 basic pokemon in your opening hand. Most of the time it's a good idea to send out an active pokemon and a benched so you won't lose because of pokemon shortage. 
 
2. HOW TO CHOOSE POKEMON: If you have a pokemon with free retreat ALWAYS send it out as your active. Why? Because you can retreat for another one to make sure you have what you need battling. If you don't have a free retreat pokemon send out a "Haymaker Pokemon". I'm sure you all know what they are, but here's the list anyway.
GRASS:Scyther(Does not need grass energy)
WATER:Lapras
PSYCHIC:Jynx Promo Mewtwo(From the Movie ONLY)
FIRE: Magmar(Fossil)
ELECTRIC:Electabuzz(Base Set)
FIGHTING:Hitmonchan 
COLORLESS: Farfetch'd
    All of these pokemon are considered "Haymaker Pokemon" because of their high Hp and ability to do big quick damage. The reason why it's a nice idea to send these guys out is because they can hold their own with little energy allowing you to give your opponent a heavy beat down while you work on your bench. If you don't have a free retreat or Haymaker pokemon it's always a good idea to  use a stalling pokemon while you build up your bench so your opponent won't get the starting advantage. If none of these pokemon are in your opening hand then send out a pokemon you drew doubles of(Ex.If you drew 2 Vulpix, and 1 Base Magmar). And if you didn't draw doubles send out a pokemon that has a 1 energy attack or you can afford to lose(Ex. Ditto or Squirtle).
 
3. WHAT NOT TO SEND OUT AS YOUR ACTIVE: Never send out ANY pokemon that is a key to the deck(Ex. Squirtle in Rain Dace) Also, don't send it out if it has a high retreat and can't hold it's own with little energy(Ex. Tangela who has a 2 retreat and needs to grass energy for it's lowest attack cost).
 
4. USE THE METAGAME TO YOUR ADVANTAGE: Send out pokemon according to the "metagame". If the "metagame" around your area is Rain Dance and you draw 1 Fossil Magmar, and 2 Electabuzz, send out an Electabuzz as your active and the other Electabuzz as your benched.
 
5. HOW TO SEND OUT POKEMON ACCORDING TO ENERGY: You need to send out a pokemon that you DON'T have the energy to build up (Unless you're playing a Haymaker in which you do send out the pokemon you have the energy for) while you build up the one that you have the energy to build up. Here is a game where this principal is used(Well, kinda) John and Tyler have just drawn there cards and you hand is 1 Electabuzz, 1 Fossil Magmar, 1 Fire energy, 1 electric energy, and 1 Scoop Up(The rest is unnecessary). Who do you send out? Magmar or Electabuzz? If you said Magmar you are correct. Let Magmar stall while you build up Electabuzz then Scoop Up Magmar allowing your damage free Electabuzz to Thunder Punch yourself to victory. Just in case your wondering why I didn't send out Electabuzz to begin with it was because Thunder Punch damages Electabuzz(Sometimes) so I didn't want damage on him if I flipped tails(I had also been having bud luck the past 3 games :-(       
 
    So there you have it! How to play your opening hand! Apply this to you game and you'll master the beginning game of pokemon in no time at all!
 
Sincerely,
~Tycoon