There are very often strong opinions expressed about what makes a good wine. At a simple level, a good wine is one that you enjoy drinking. Read what a professional wine taster says on the subject.
Balance is probably the easiest answer.
That is the tricky thing. Of these three, taste is by far the most complex, but sight and smell are powerful. The wrong colour or the wrong smell enable a wine to be discarded without taste even being involved. So, take your glass, tilt it against a white background in a bright room, and look at the colour. A young wine that does not have a vibrant, sparkling colour is almost certainly bad.