Money issues can put a serious strain on any relationship. When a young couple decides to move in together, it is very important to discuss some serious questions regarding money. Who should manage the household budget? Should they keep their separate accounts? What happens if one of them gains significantly more than the other? Who should decide what to spend on? Should a woman pay for a hairdresser on her own? And how about the car maintenance? It is very important to set common goals before serious problems evolve. Some couples simply split every single spending, some others split only food and household expenses. There is no such thing as the only good solution, the key is to agree in advance on the most important issues.
It is a good idea to decide whether you want to save some money on the long term, or on a short term. For long term savings, it is advisable to set up a new bank account to which both of you can transfer a given amount of money every month. Whereas for short term savings, it is enough to make a decision about what to save for (vacation, new car, etc).
Many couples decide to keep their separate accounts, simply because it is easier this way to keep track of their own spendings. These couples generally split the food and household expenses, and keep the rest of the money for themselves. It is a very worry-free arrangement, indeed, as there is total equality. It will work though only if both of them has a job, and more or less the same salary.
Some others think that constantly keeping track of spending kills the romance of the relationship, and prefer to handle the money without thinking of whether it was originally his or her salary. It require a little bit higher level of understanding and acceptance between each other.
Whichever solution you choose, the important thing is to agree upon something, and then stick to it. Neither solution would work without completely trusting each other. It is not a good idea to keep things from each other, but grilling the other about his/her money, asking for details all the time is a bad idea, too.
Personally, I think that it is better to be generous from time to time, than letting the relationship be constantly about money.