Yeah, unfortunately, even as a casual gamer, you kind of need to understand the system and handle your upgrades strategically. I'll try to post a few tips towards that end.
1. Take a good look at the cards for each class, starfighter, hero, and hero ship. Look at the upgrades they provide and consider how that will play
for you. Maybe you prefer to be more durable, maybe you want to hit harder, maybe you like rate of fire. Whatever. Just look at the stuff available, and carefully consider how you will want to play.
2. Spend your credits wisely. The credit drop rate is really pretty slow. The RNG nature of the crates themselves makes this more difficult, because you may open a crate with junk you don't want. With this in mind, BUY HERO CRATES ONLY. Do NOT buy the trooper crates. They're way too expensive to justify it, and you still will get stuff other than hero gear from the hero crates. The whole crate system is a crap shoot, so you might as well roll the dice with the cheapest entry fee.
3. In my opinion...it's a waste of credits to buy heroes. The only one I bought was Iden, because she was cheap. I haven't used her yet, though, and I only have her because I prefer her to Fett (can't get the hang of his rocket pack). Outside of Heroes vs. Villains (HvV), you need a LOT of "battle points" within each round to play as a hero, and you may not even get to play as them because someone else got them first. So, unless you're gonna play a LOT of HvV, there's no real point (in my opinion) to spending 15000 credits on a character you'll almost never play. That 15000 credits can get you 7 crates instead, which seems much more worth it to me.
4. Ideally, you want to be able to use 3 cards per class. That requires you to level the class up, which leads you into a complicated system for class upgrades. So, here's the deal. You can use two cards when your class is level 5. You can use three cards when the class is level 10. Your
class level is based on the total number of "pips" in your class' card inventory. So, if you have an epic/purple/tier-4 card, and a common/grey/tier-1 card, your class is at level 5. If you have two uncommon/green/tier-2 cards and one common/grey/tier-1 card, same story. Get the picture? Ok, so, here's where it starts getting tricky. You can occasionally pull upgraded cards (tier 2 and tier 3) from crates. You can also craft tier-1 cards, or upgrade your cards. HOWEVER, you can only upgrade your cards when (1) your
class level is high enough, and (2) your
global level is high enough. It's an annoyingly complex system, but once you get it, it's mostly just time consuming to deal with, rather than difficult.
5. You can craft cards without getting them from crates. This will give you a Tier-1/grey/common card. You can upgrade those cards to a higher tier, assuming you meet the upgrade requirements and have the requisite number of crafting parts handy. You get between 35-50 crafting parts from any crate except the daily crate, which gives you only 5. Duplicate cards from crates will give you credits, rather than crafting parts. That's a change from what DICE said they'd do after the beta (they said it'd be crafting parts).
6. My advice is that you focus on using crafting parts to craft the specific cards you know you'll want to use, if you aren't getting them from crates. This guarantees that you're getting what you need/will use. The card drops from crates can be used to increase your class rank, so that you can equip all of the cards you want to at once. You may also still get lucky by pulling higher level cards that will help boost your class rank. But if you're just not having luck with the crate drops, don't sweat it. Craft the cards you want instead, and upgrade as you can.
7. The cards make
a difference. But they don't necessarily make
the difference. That said, the game is designed to make you
think they make
the difference. For example, the thermal detonator has a card that, at epic level, makes its blast radius 30% bigger. 30%!!! That's huge! Until you ask yourself "Wait, how big is the standard blast radius?" If it's only, like, 2m, then you're only going to 2.66m. That's certainly helpful, but it's not the "OMG!!! HUGE!!!" upgrade it might initially seem. All that said, the cards do help, especially with the heroes and the starfighters, where they make a much bigger difference. Darth Maul has a card that has him take less blaster damage, which is important because he can't block blaster shots (for whatever reason). Vader has a card that gives him health back for every kill he makes. The starfighters have cards that make missile locks take longer to lock on, with the lowest level increasing lock-on time by 50%, and the second tier increasing that to 100%. A lock may take 1.5 seconds normally, and now it'll take 2 seconds with the basic level card. That may not seem like much, but it can make a huge difference in dogfighting. All of this is why I advise crafting specific cards, so you get what you want/need.
8. The Arcade mode can give you up to 500 credits daily. That's about 1/4 the cost of a hero crate (a little less, actually). You can "game" the system and get your daily 500 pretty easily, though. The Dark Side's final challenge at the toughest difficulty level has a 3-second timer (it doesn't start until you actually attack an enemy). You can kill one guy, which will get you another 3 seconds, and then just let the timer run out. Boom. 100 credits for 6-ish seconds of "work." You do that five times, then move on.
I've been playing between 1-2 hours each night since the 3-day head start (I preordered the Elite edition). I've stowed away about 10,000 credits "just in case." I haven't completed every milestone, but I've completed a bunch. Even relying solely on credit drops, I can usually manage a crate a night. It's slow progression, but using the crafting parts has helped some. When all of the milestones are done, I'll have a decent "hand" of cards. They won't be epic level, but they'll be mostly "uncommon" or "rare" for the ones I use. I don't sweat the rest, figuring I'll unlock them eventually. Maybe. The progression system is incredibly stupid and badly designed, and was built to encourage now-disabled microtransactions. It sucks. But it can be managed to allow you to still have fun in the game regardless.
Map/game balance and matchmaking...well, that's a different story.