It is important to select products which meet with your living needs and that maintain or improve the look of your home. Security is of great importance and as many windows and doors come with high security locking systems, make sure you are happy with their operation.
If possible always ask to see the product in a showroom or installed.
Glazing and frame insulation is important as it will effect your heating costs, basically the higher the insulation you can afford the more comfortable and lower energy costs will be realised.
If you are replacing your old windows, most new aluminium windows will offer you better insulation, but it is always wise to check what are known as 'U' values. These are a value of insulation and the lower the number, the better the insulation.
Always obtain several quotes from different suppliers and try to make these like for like so you have a good understanding of the costs. Lead times may also be of importance especially if you are choosing specific colours for your project.
As explained under the page Aluminium Finishes there are two basic finishes for aluminium, the popular powder coated finish and anodising. Choose the right finish for your project and the location, remembering the requirement for a marine grade application close to the coast.
Links to further reading