Always make sure you buy a swimsuit that is of a good quality. The more spandex there is in your swimsuit the better, because your swimsuit will hold its shape and form longer.
Remember to always wash your swimsuit by hand after each use with a mild washing powder (preferable one that specifies hand wash). Once you have washed out your swimsuit, hang it in a bathroom and not outside, as the sun will cause the colour to fade. The sun also negatively affects that elasticity of your swimsuit.
Have more than one pair. The reason behind this, is that swimsuits need at least 24 hours to dry properly before being reused. The 24 hours also allows the suit to get back to its original shape and form.
Yes we all love laying in the sun, having a swim in the pool and then laying in the sun some more. If possible though, you should always do your sunbathing before you have a swim. This is because the combination of the sun and the chemicals (from the pool) cause your swimsuit to wear out.
With these tips in mind, there is no reason why your swimsuit can't look new all summer long.