Let's have a fitting!
1) If you are not sure about what size to buy, remember, when in doubt buy a larger size.
2) Jeans and pants made of cotton may shrink during the first wash or dry cleaning. It's a good idea to wash, dry, and try them on before the day of your appointment. Wool may also shrink, the first time it is dry cleaned.
3) Think about the heel height of the shoes that you will wear with them. Winter shoes may be higher or thicker which will require a longer hem length.
4) Feel free to bring the other parts of your outfit with you, to try on, especially if it is for a formal occasion.
5) After being altered, the workmanship should look as good as it did when you bought it.