I just started a few days ago on smutstone.com. I spent like $20 the first full day that I played. I got 1st in the tournament. Got to like the half way point of map 2 and got stuck. Today spent another $50 and won tournament again. I realized the best way to advance if you spend real money... is to use the red gems to buy energy. Use that energy to farm and collect needed items for leveling up. 40 gems gets you 120 energy. Say you farm world 2... that's 8 battles you can do at 15 energy. Say you only play ones you know you can win... that's a minimum of 2074 on world 2. That gives you 16,592 gold plus if you get 3 stars every time that's 35 tournament points each so that's 280 tournament points... so 280 tournament points and 16,592 gold PER 40 red gems. Otherwise you can buy gold with red gems for 50 gems it's 8,000 gold (that's less than half the amount of gold for 10 more gems and no tournament points).

In other words... if you spend money... use the red gems to buy energy... it will payout the most for the money.

If you are free to play on the other hand... when you first start just go as far as you can with battles and save up all your gold and such... don't level up or seduce. Keep farming the ones that you can beat to get items/gold. When you have enough saved up... open all your packs, seduce stuff, level up stuff. You should get top 3 of tournament and get the good cards then. Just repeat the process and keep winning the tournament. The tournament prizes when seduced and leveled up gain the best stats of all cards.

Also build the best deck you can for each card type and farm the dungeons. You want to seduce more than level up... as it raises stats more. This means you can't just seduce/level up your specific deck... you have to level up and seduce all cards. It's probably best at the very start of the game to focus on your deck only, but eventually you want to go out into upgrading all cards.