You can change methods every day if you get bored from one. You can meditate alone or with a group of people. Just relax and enjoy it without waiting for any huge results. In some time you will feel the difference between you before and now.
Try to meditate before sleep (you can do it right in your bad, just lay down with your back straight and relax) and while doing this think to yourself "I will be conscious while sleeping". In some time of practice, it will work and you will see the most beautiful dreams ever.
Just concentrate on the taste in your mouth while you are eating. Don't make any evaluations to the taste (good or bad, sweet or spicy), just open your mind and feel it. It is hard to concentrate on the taste for a long time first, but after some time of such practice, all food will taste like it tasted in your childhood.
Try Zen of Seeing by Frederick Franck. Many people think it's the best books ever for drawing meditation, it will open your mind and make you more relaxed, you will see the world around you in a new spectacular way.
Each method of meditation is good for making it easier for you if you have mental problems, and they can even help you with your practice.
Use your obsessive thoughts or hard emotions as objects of meditation. Just watch them without any evaluation and in some time you will understand that your thoughts and emotions are not that powerful and you can control them.
Concentrate on your negative emotion while meditating and soon you will understand that you can't concentrate on it for too long and it often happens that you start thinking about your laundry or something like this. This way you will understand that all your feelings and emotions are not that powerful and you can control them if you watch them. You can use this method on the go if you are too busy for formal meditation.
Try to meditate on a picture of the holy person you like. Just put the picture in front of your eyes and try to concentrate on the imagine. After a few minutes of looking at the picture just relax your mind for a minute or even less and then again concentrate on the picture and so on. You will feel very relaxed and cheerful after it.