Whatever you do make sure the suit fits you 'perfectly', i too often see people wearing suits that they just get of the rack and go 'meh, that'll do', it just doesnt fit their body right and looks bad. Go for a slim fit style suit if you can get your hands on one.
A suit that fits you well will look 10 times better. Hence why people get their suits tailored etc.
Black suit + black shirt is ok only if you can pull it off, shirt should not be the same texture as the suit itself, it should be 'brighter' or more contrasting in a sense. If your of medium-tall build, a standard no pattern black suit will be fine. If your short-ish/abit chubby etc, then a suit and/or a shirt with vertical pinstripes will make you look abit more slim and taller.
If you are abit bulky/large, an all black suit with black shirt will also give you a slimming effect. Be sure to add some color such as a silver tie (so it doesn't look like your contract killer or going to a funeral), don't have the tie too bright, it will stick out like a sore thumb, if your using say a silver tie, have a darker texture tie, perhaps with some dark grey/charcoal diagonal stripes. Slim ties are the way to go, notice i said slim, not skinny, nothing under 2 inches. The key is colour and texture coordination.
...shit...too much Queer Eye...