If you are replacing damaged skirting boards, you can take a piece of the original skirting to a carpentry workshop where they will copy the profile for you and make skirting to exactly match what is being replaced. This however can be costly as there will be a set up charge, and also take time. If you are an experienced DIYer with a full set of router bits, you can router and fashion your own skirting. A better option maybe to try to find a style of skirting that if not exactly, almost matches what you have. If you are replacing skirting in the whole room you do of course have the option to choose any skirting design you like.
Here are some tips for making a perfect job of skirting in your room. Like all DIY jobs, it will take time to get it right but the result will be worth taking your time over.
Get the right height of skirting boards for the room - tall rooms have deep skirting; shallower rooms have shallower skirting. In a tall room if shallow skirting is used, it will make the proportions of the room look all wrong, especially if used in conjunction with dado, picture rails and cornicing. As a very rough guide, the top of the skirting to the dado will be approximately 2-3 times the depth of the skirting.
Buy mixed lengths of skirting board to suit different wall lengths so that you do not end up with too much wastage.
When joining pieces of skirting together in the corner of a room, corners can be mitred so that the two pieces join at an equal angle of around 45 degrees. This is quite fiddly to achieve as corners in the rooms of period houses do not tend to be exactly 90 degrees. As a result there is usually a requirement to fill any gaps and it may be difficult to achieve a neat result. As an alternative which you may find easier to work with, one piece is cut at 90 degrees and the other one is joined into it having been cut to the profile with a coping saw.
When joining two pieces of skirting together in the middle of a run it is neatest to use a diagonal cut to join the pieces rather than a vertical cut as the join lines will be less noticeable. If your wall is not completely flat, you might have to build out from the wall with another piece of wood to give a flat surface to attach the skirting. (This would be used for very uneven walls). Similarly your floor may not be completely flat so you may need to trim the skirting to the floor profile before fitting.
It is best to prime the skirting before fitting, as it is easier to paint when off the wall than when on it. This also means that you can prime the back of the skirting which may make it last longer and protect it from any moisture ingress. To fit your skirting, the best method is to glue it onto the wall, fill, sand where necessary and paint on your top coats. Several coats of paint will be required as skirting in general will take lots of wear and tear. Beware of damage from vacuum cleaners and children. Acrylic paint is recommended as it gives a very durable finish on new skirting.
The Victorian Emporium sells the full range many different profiles of skirting for every room in your house.