Plants vs Zombies features plenty of strategy so here is some advice on how to be better skilled in some areas, like getting money, using the interface, reading the almanac, and dealing with tough zombies.
Make Money In Plants vs Zombies
You will have to fill your pockets with cash if you want some exclusive items at Crazy Dave's shop. At his store you can purchase all kinds of goodies, like additional slots so that you can choose more plants for levels, powerful plants that will bolster your offense and defense, and other unique items that can help you. His items are expensive but the good news is there are several ways to earn money, so it's possible to afford them. The key is to work hard at several money grabbing activities available for you.
Collect Coins
Every stage gives you an opportunity to make money, one activity being when certain zombies die, they leave a coin for you to collect. Silver coins are worth $10, and gold coins are worth $25. If you're able to collect most of them, you can get a hundred dollars or more. What could distract you from the coins is collecting sunlight, planting your garden, and fighting zombies; if you need money, don't ignore the coins zombies drop for you. Keep your eyes not only to the left side of the screen, but also the right, where silver and gold coins will be popping up on screen as zombies get brought down.
Mini-Games and Puzzles=$$$
You can also earn some gold in the mini-games and puzzles, which will have to be unlocked; coins can be collected here as well. Every win there should be rewarding since you will receive plenty of gold. These games are the best way to fill up your wallet, so play them quite often if you want to make money in the thousands. Once you unlock Survival mode, skillfull use of the Money Flower will get you tons of cash. Tending to your Zen garden will also cough up increasing amounts of cash.
Lawnmowers Give You Cash Too
If you don't use your lawnmowers during a battle, you will be rewarded $50 for each one that is left. If you saved all five lawnmowers, you will be rewarded $250. Even though the lawnmowers can be used as a safety net, to run over zombies that manage to get to the end of that lane, you are also forfeiting $50 for every lawnmower used to kill enemies. So think ahead and see if you need more money to make purchases. If you do, then try to build a better army against the zombies, and don't rely on your lawnmowers to take care of them.
When you are willing to make money by working through all these activities, you should be a rich man and a busy customer at Crazy Dave's shop. Remember, most of what Crazy Dave sells runs into many thousands of dollars, so it won't be easy to buy his items if you don't make an effort to earn money.