If you're just getting back into the game, you can still use your old cards in casual play at just about any league (provided your opponent agrees to play an unlimited match).
As for standard (modified) play, one good way to get familiar with recent cards and the format in general is to watch recent YouTube videos (I highly recommend the channel TheTopCut, which uploads videos from PTCGO, the online game, around twice each week), or to read decklist threads (Which you can find in the Deck Garage forum) and articles (which you can find on a variety of sites, such as http://google.com/.com and thetopcut.net).
Another great way to get into the game, while also getting your hands on some brand new cards, is to attend a pre-release events. Most leagues will hold a pre-release tournament 1 or 2 weeks prior to the release of a new set. These tournaments give you 6 booster packs from the set and have each player build a 40-card deck using only the cards you pull (basic energy being provided freely, though you must return them). Since everyone's on an even playing field (and since these tournaments are always for more fun and casual play), you don't have to worry about what you bring. Though I would bring/buy sleeves if you want your new cards to stay in good condition.
The next pre-release for English cards will be for the Furious Fists set, and will take place on the weekends of August 2nd-3rd and 10th-11th, depending on the specific league hosting it.
Lastly night maintenance is no longer legal, but Super Rod (Noble Victories and Dragon Vault) is an exact equivalent which IS. However, Super Rod will unfortunately be rotated out after the next rotation which takes place this September 3rd. We are rotating to Boundaries Crossed-On. Once it is rotated, there will be no trainer cards in the format which can retrieve both Pokemon AND Energy from the discard, sadly. However, we will still have Max Revive and Sacred Ash for Pokemon, and Energy Retrieval and Superior Energy Retrieval for Energy.
Hope this information was helpful.