NASA has taken to its 'NASA Goddard' YouTube channel to release a great guide to 'near-light-speed travel', and what you need to consider.
The video NASA has released is quite funny, as it has assumed the viewer has already worked out how humans can travel at near light speed, which is 186,282 miles per second (299,792 kilometers per second). At the moment, humans haven't yet worked out how to effectively transport humans throughout the cosmos at those speeds, but NASA's video gives some pointers to consider once we figure it out.
The animated video touches on some facts that will need to be considered once humans reach this level of travel. NASA reminds us of travel times, the distances between popular destinations, and shielding for the spacecraft. If you are interested in watching the video for yourself, check out the above link. On a personal note, I really like these short animated videos containing a nice bite-size amount of interesting facts. If NASA happens to read this, keep doing these!