Hi Burst - I think I'm in a pretty good position to give you advice as I just started 3 months ago and am totally addicted.
It's hard getting started, everything is very new and exciting and you're trying to drink from a firehose while at the same time running on a treadmill that's going way too fast. All I can say is enjoy the discovery and the newness because once you start figuring it out, you'll look back on this time with fondness.
Having said that, expect to lose some as you're starting out. It's hard, not knowing what cards you want exactly and even harder trying to figure out how to get them. I would definitely watch online matches on youtube. Just search for whatever pokemon you're interested in, and you'll probably find a bunch of videos people have uploaded, all chock full of really imaginative combinations and interesting ideas (which, as an aside, is part of why I hate Night March - all of these Night March decks are exactly the same, there's no creativity). These are all veteran players who (for the most part) have learned through experience the right time to play the right cards. I've learned a ton from watching them, that's one thing I would absolutely recommend.
I look at the deck garage here at PokeBeach as well as other (less quality) sites and compare deck lists. I find it fascinating that two decks will have the same pokemon but many different trainers. Learn the different trainers, spend time thinking about how you might be able to use them with your Pokemon.
Finally, play as much as you can, and try not to concede, even if things look grim. You always learn more from your losses, and probably every other day I have a game that I'm able to pull off even though I'm several prize cards down. Go have fun in the moment, and good luck. Oh, and always run 4 VS Seekers.