Monpla Smash is an extremely fun new monster collector game by GREE Inc, creator of many old school browser-style RPGs for the iPhone and Android OS. This one is a bit different, though, as Monpla is mostly about the single player mode and the monster collecting, putting you into a series of quests where you fight monsters, use smash attacks to collect more monsters, beat boss monsters and defeat the evil trainers.
Stars are a form of currency in the game – mostly, they are spent on leveling up your monsters by merging one monster card with one or more other monster cards, where the first card is the gainer and the other cards are the sacrifices. Hearts are used to get more monster cards and increase the size of your collection.
Completing quests is the main way to get stars in the game. Some quests have more monster battles than others, so you can maximize your star count by doing the quests over and over which have more monsters. Also, some quests take longer than others to complete, especially boss quests, so do the boss quests over and over again in order to fight the maximum amount of battles to earn stars. Boss battles on their own earn a huge amount of stars for beating them.
Also, try to get perfect smashes on every battle that you do for a very large bonus. If you catch a monster with the perfect smash attack, then even better. To further maximize the amount of smash attacks, send WEAKER monsters on the quests (weaker as far as attack power goes) so that it takes more hits to kill off a monster. This means that smash will charge faster.
To get hearts, do the same thing as above, since you earn hearts in levels. At the end of each level, you will be prompted to add friends. When this prompt happens, add everybody that you see. Do shorter quests to minimize the amount of time you spend between adding people.