One of the most important aspects of working out is choosing the appropriate workout attire that will be comfortable during the exercise you are doing. A lot of this is personal preference depending upon what is comfortable to you. You can not just look at your workout buddy's gym attire and then buy the same things they have otherwise you really know that those same clothes will be okay for you. There are a few things that will help you keep from having to go through the hassle of returns.
One of the first things you want to look at is fabrics that will move moisture out away from your body which will keep you dry and comfortable for long and sweaty workouts. If you are doing high impact aerobics or running you will want a fabric that will remove moisture as well so that you will stay as dry as possible. This type of apparel will be more expensive but it will be well worth it. If you are not going to be working out so hard that you sweat a lot then you can go with a blend of polyester, cotton, and spandex.
The next thing we want to look at now that we know the appropriate fabrics is how to choose the right cuts that will be good for the activities you are doing. If you live in an area where it is cool and you will be exercising outdoors you will want to buy the exercise apparel in layers that you can remove as you heat up and tie them around your waist or place in a light backpack. The clothing layer that is next to your skin should be either long sleeve or a tank top hanging upon the weather and temperature. You may choose to wear a sweatshirt over the first layer which can then be topped off with an all weather jacket if you are going to be in rain, sleet, or snow.
As far as pants go there are a great number of choices in pants that wick moisture and some of them even come in thermal styles to help keep you warm which can be worn by themselves or with another layer. If you are training in the cold be sure to wear a cap or hat to keep your head warm, much of our body heat is lost through the head when it is cold.
If you are training or exercising in a commercial gym or in your own home it is also smart to dress in layers so that you can remove clothing as you warm up. When weightlifting or doing aerobics especially a t-shirt can become tight and rigid due to being wet and will give you some skin irritation. If you dress in layers you will always be comfortable no matter what climate you are in.