I write this with trepidation as everyone has an opinion about websites, what they should include, and what they should look like.
There are plenty of choices. Of course a lot depends on your budget, what sort of business you have, and whom you consider your target customers to be.
If you are selling stuff I would always recommend you talk to a professional web designer familiar with shopping carts and all the other bells and whistles required to make an on-line shopping site run smoothly. Ask around and get recommendations.
If you are mainly selling your expertise, I would still recommend you ask a professional if you are not confident with the free and paid-for software available to build a website, or if you simply do not have the time to do it yourself. It comes back to that old adage that you should concentrate on working on your business (that is doing what you do best) and not working in your business just trying to do all the chores. If building a website is a chore, don’t do it. If it is fun and almost recreational, then go for it.
There is quite a lot of free software available and most of the hosting companies have an assortment which can be installed automatically as you wish. I will not say that it always goes to plan. Sometimes you will need a support ticket because your host ran the wrong routine, but generally it works.
I do not have experience of anything other than WordPress. There are plenty of free themes available, and quite a few firms have premium paid-for themes you can try, but if you need a WordPress tutorial there are better teachers than I. Email me if you need help finding someone.
What about the content of your website? If you trade in a particular niche product area or if you are sell particular services or knowledge, you should post articles showing your expertise. Some people worry that if visitors to the website learn how to do something from reading your articles they will not buy from you. Actually these will be people who would not buy from you anyway. They will go away and mess up in an amateur way because they did not realise you cannot write the entire manual of your expertise on a website.
You will get customers who buy from you because they have a particular problem and they have read your articles and know you are the person to solve their problem. That is called content marketing. Writing in a niche attracts people who use the search engines to ask questions. Believe me, I know it works.
Talking of search engines, in WordPress and other website software you can get tools to help your Search Engine Optimization (SEO); to get your website found. You do have the option to hire an SEO specialist if you wish. As always, if you do not know what you are doing, get specialist help.
I believe virtually all businesses should have websites. They are our on-line brochures, they help us be found and if our potential customers have already heard of us, they can learn more about us. Then, when they call, they will have qualified themselves to buy already.