Many people dream of building substantial wealth over the long term. From paying school fees to buying a dream home, it could help! But finding a way to make that aspiration come true can be challenging. I think buying bargain UK shares could potentially be what I am looking for. There are two key ways in which owning shares could help me build wealth. One is an increase in the share price and the other is receiving dividends. Neither is guaranteed though. Indeed, the share price may fall. So selecting the right shares is critical to long-term success in investing. So how would I try to do that? If I was to summarise in a single word the thing I would most look for when hunting for UK shares to buy for my ISA, it would be value. Value does not necessarily mean a low share price, though it can. Rather, it means paying less for something than it is worth. Ideally, I would be paying substantially less than it is worth, as that would increase what Warren Buffett refers to as a margin of safety. But when looking for value, I would also be keeping an eye out for...