Sure, if you win the game, and want to go back and cheat to have some fun, then have at it. But if you haven't won the game yet, don't try it. If you want more money, there are many ways to earn money. If you want the weapons, they can be found for free all over the map. There really is no reason to cheat. Every mission is set up in a way that is winnable if you've taken the time to learn the appropriate skills. If you don't learn those skills, then you are going to fail the next mission too - because the skills all build on each other.

The game isn't meant to be won in a weekend. Would you really want to pay $50 or more for something that only lasted 2 days? It can easily bring you months of gaming fun which is a GOOD thing. Work your skill levels up, work your health levels up, and don't try to race through the missions. You'll find your satisfaction in winning the game will be incredibly powerful if you do it through your own skill - and then any other game you play will benefit from your enhanced reflexes.

Grand Theft Auto San Andreas Walkthrough