Of course growing up in the West you're bombarded with images of the White Christ, so I suppose that's what he looks like in my imagination. Historically however, he'd resemble a short, olive-dark skinned man of Middle East origin, probably with curly black hair. This is for a variety of reasons:
1) People were much, much shorter at the time (average height was probably no more than 5 feet). Our artificially fortified and enriched foods allow us to grow to our maximum allowed height, a trend which started after the industrial revolution. Ironically, this is why the Shroud of Turin most likely does not depict the true Christ as it outlines a man over 6 feet tall. He would have been a fearsome giant back then (like Goliath, who was probably only as tall as Michael Jordan) whereas the Bible describes him as having common features.
2) There are Caucasian Jews today because of mixing and interbreeding with Europeans after the Jews were conquered and scattered several centuries ago.
3) Being from the hard working class (his father was a carpenter), Jesus probably would have appeared as someone used to hard labor, probably with sinewy hands and a lean, sunburned figure. It is highly unlikely that he would have had those tender, effeminate features we see in popular depictions. Only the idle nobility could come anything close.
And contrary to the hopes of some in the Black community, Jesus was most definitely NOT a black man.