Depends on your budget and whether you want originals rather than prints.
The internet has many, many artists selling their paintings, both originals and prints, so you could have a look at what’s available. Also visit art galleries and the end of degree art shows at art collages.
Find a good framer who can advise you about what frames suit each picture. Mounts are important too, look at colours and the use of double mounts. I pick up good frames from charity shops also.
It took us about 5 years to build our art collection, all originals. We bought from local artists and also on holiday. Our favourite painting came from a restaurant which had paintings from local artists for sale. One caught my eye and, as the evening went on, I liked it more and more. I bought it (at a reasonable price of £750) when I paid for the meal - our most expensive meal ever!