First of all, when looking for the good putter to play, you need to feel comfortable when holding it. Put yourself in a putting position and simulate a putt. It is sometimes a bit difficult to explain why, but some putters are just don’t fit. Don’t go against your feeling, if it doesn’t feel right, it isn’t. So my advice would be, move on and try another one.
You sometimes hear that the size doesn’t matter? Well, here, it does! and it’s not the longer the better of course. You need to find the size that suits you well.
There are lots of theories about the length of the putter which should be more or less the height of your hip. That can help a bit perhaps, but I believe it really depends on you too. Your arms, the position you feel comfortable with etc.
Be especially careful not choosing a putter that would be too long, The ideal putting position being quite bended, a longer putter would force you to stand too straight.
There are two families of putters: Blade-shaped putters and Mallet-shaped putters. Both have their advantages, and again, the choice will be all yours when you hold it.
Blade-Shaped Putters are the classic putters, they are usually lighter than Mallets and offer good precision. Especially when the weight is split on the sizes and not in the middle.
Mallet-Shaped Putters offer nice shapes and people can fancy their design. But if they are widely used, it is also because they offer more stability. So a little bit more precision. Being than Blade-Shaped Putters reduce the club’s small parasite movement that may happen when you putt. Also, the aiming line usually drawn on it is convenient and can provide some help.
Most of the putters you will find in a mini golf course are Blade-Shaped, sometimes all of them. And there is a very good reason for that. Mallet-Shaped Putters are nice to use on a real green and may show more advantages. But a Blade-Shaped one is much more convenient on a mini golf course. Indeed, you sometimes lack space between the ball and the border when playing mini golf. And although our rules allow you to move you ball a bit. A thiner putter will allow you a wider movement.
You will see many, many, many different putters.
A lot of factors are to take into consideration. But clearly the most important is how you feel when you hold it. Putting is about skills and experience, yes, but is also highly psychological. A non quantifiable thing about a putter is the confidence it gives you. And that can change a lot the way you putt.
I have seen very, VERY good mini golf players playing with the most simple, old putters. The reason was just because they liked them and feel like it is the one that fit them,
Where to buy good equipment? In the countries where they are established, I really recommend Decathlon stores. They offer a very wide range of product and in most of the store you can try the equipment. Golf courses shops are a good alternative too. But they frequently don’t have beginners’ equipments and the prices are usually higher.