1.  If trousers too tight at the waist, you can release the pleats or darts.  It may or may not have a band.  If there is no band it is easier to unpick the darts and put a panel in the facing or unpick the lining darts. For trousers (or skirts) with a band, unpick the band from the button end around to the button hole end, but not all the way.  Leave the buttonhole end attached with enough room for you to get in and sew the band back on.  Release the darts or pleats the amount you need, and sew the band back on, putting an extension in the end.  Usually the original band will hide the extension.  Try to use fabric of a similar colour and weight.  I actually pin the band back on with the pins facing forward, and I sew with the band on the top so that I sew back into the original stitching.  You will never know that the band has been unpicked if you do this.

2.  If the trousers are too tight in the crotch area, or you have what is called a camel foot appearing around the crotch area, this is usually due to the crotch being too tight.  This means you need to lower the "rise" of the trousers.  The rise is the seam that runs from the centre front to the centre back.  If you turn the trousers inside out, then pop one leg into the other with right sides together, you will have easy access to the rise.  Lower the rise without taking in too much around the tummy or bottom area.  In other words you are going to begin sewing about 6cm (2 ½") from the crotch join front and back.  This will lower the rise and give you more room. To be honest I would not lower a rise more than 4 cm (1 ½").

3.  Put a panel down each side of the trousers, but use a fabric that is a good colour match or a contrast colour that works with the trouser.  Something that looks great is a heavy lace panel with a fabric behind the lace. The backing could be any colour.  I have inserted lace down the sides of trousers in this way and backed it with a skin coloured "two way stretch" called peek-a-boo.  It looks like you are looking at the person's skin but in reality it is the stretch fabric.   There are some fantastic fabrics out there so use your imagination.

4.  What about opening out the side seams of the trousers and sewing loops on the sides like the back of the dress.  Then making a long cord, or buying some and threading it through the loops.  If you are concerned about exposing your skin, sew some stretch fabric underneath.  Make sure that the stretch fabric is smaller than what you want, so that the fabric doesn't bunch if the trousers become too big.

Happy altering
Judith aka genie