1. Define your needs
Before chatting to a web developer or design about what they think the best solutions might be for your business, it always helps to have a good idea yourself. Work out as exactly as you can what you need, what your estimated budget is and any other logistics like when you want it done by.
Being prepared will benefit you in several ways; you'll be able to save timing searching only for developers who offer exactly what you need, your initial chats with agencies and developer will be more efficient, and you will better avoid being sold add-ons and extras you don't really need.
2. Put quality first, not cost
As with most things in life and business, you get what you pay for and, unfortunately, the website production industry has a nasty case of the 'race to the bottom's. While it's not black and white, cheap = bad and expensive = better, you should always be wary of following the cheapest quote. In some instances you might be stung by hidden extras, receive a website that isn't worth a penny or just be dealt with as part of robotic processes rather than with genuine interest and effort.
Of course, money is a big factor in any business decision, it's still important. Websites are a bit like cars; everyone would like the brand new, top of the range model but few can afford it so they buy cheaper.

If you go right down to the bottom and buy a 24 year old, 150,000 mile, £450 banger from Derek down the road, chances are it won't last long and you'll have to spend more money fixing it or replacing it. Buy sensible, not cheap.
3. Ask lots of questions
Before hiring any agency or freelancer to build your new website you should ask as many questions as you can think of, and then make sure you've asked these too:
- Do your quotes include hosting?
- Do I get to keep the website? (I.e. can I download the website and take it anywhere else or will it only work with their code/on their servers)
- Will you maintain the site after it's deployed? Does this cost extra?
- Will I be able to easily edit the site content? (Text, imagery, pages etc.)
- Are the websites you build:
- Mobile-ready and responsive?
- Optimised in terms of performance?
- Built for SEO?
- Copies or templates?
- Accessible?
- Secure?
- Cross-browser compatible?
A good studio or freelancer should be able to answer these questions easily and without getting in a huff. If they take issue with you asking questions then look elsewhere.