In general, tips generally vary from deck to deck, as they use different strategies, and deck practise is the main tip. As GadgetJax pointed out, do not feel binded or restricted to the cards you use; it's your choice and your freedom! Also, don't feel like you need to go and buy cards. If you're low on cards, then I suggest buying a theme deck. They come with Pokemon cards, energy and trainers.
However, have a look at a few strong decklists - or even post one - around PB (such as
here). Most of these decks focus on one or two types, using around 10 to 15 Pokemon, 10 energy and 25 trainers.
Ideally, you should have multiple of the same Pokemon (for consistency) in a deck, but remember you cannot have more than 4 of the same card in your deck (except basic energy). Try and find cards that compliment each other. The link in this paragraph shows some popular and competitive decks with complimentary cards.
Energy is generally kept low, as trainers help draw it, and you often don't need heaps. With trainers,
here you can find some note worthy cards. But... in general, you want to have around 10 or so support cards like N and Juniper/Sycamore (cards that draw more cards). The rest of the trainers really depend on the deck.
These links -
here and
here - has some really good tips in making decks.
A few tips while playing include:
- Always check weakness and resistence! They are often overlooked.
- Try and attach energy (unless via ability or other card, one per turn)
- Think about which Pokemon are best in which situations - maybe to counter weaknesses or abilities
- Practise! The more you get to know your deck = the better you play!
- Supporters (particularly draw supporters) should be played most turns - but remember you can only play 1 supported per turn, so choose wisely