There are many factors that will affect the effectiveness of your website design. The way a website looks, its colour scheme, its copy… but first of all, you need to work out what effective actually means to you. It might be that you want to get good quality leads that you can convert, or you might want to make sure you have a website that reflects well on you if people conduct a branded search. This will then dictate the way in which you design and build your website.
Once you have decided on what you need your website to do, you can start to consider how you are going to make sure it does this. Website load speed is important regardless of your aims, because you will lose visitors if it takes a long time to load. If you want to generate leads, you will need to prioritise user experience, and for a brochure website, make sure it looks highly professional.