Buy an inexpensive basic machine or a used machine to start out with. After you have gained some experience, you will know what features are important to you and will be able to make better choices when investing in a more expensive machine. You can often trade-in your old machine or keep it for a back-up when the other is being serviced.
Take fabric samples with you to use when trying out machines. Dealers will usually demonstrate using fabrics that are easy to handle, giving the best results. In addition to watching a demonstration, you should test sew using the types of fabrics and techniques that you plan to use.
Think about what kind of sewing you are planning to do before you start shopping for a machine. Make a list of features that you need and/or would like to have. Rank them in order of importance. This will help you when comparing machines. Remember, the most expensive machine isn't always the best for every purpose.
Research before you go out shopping. Almost every sewing machine company has a web site where you can look at the current models and features. You will also be able to look at what accessories are available. This gives you a broader view before you go to look at the limited selection that is available in your area.
Many sewing machine dealers take trade-ins and have a selection of used machines. Used machines can be a good option if you are on a limited budget. When purchasing a used machine, make sure it has been serviced and tested by a qualified technician. Also, be sure that your used machine comes with an instruction manual.