Some satellites are old and have been in orbit more than 30 years. Satellites known as 'Iridium' can be visible in broad daylight unlike any of the thousands of others in orbit. Such 'one power flashers' are a remarkable sight to see. These satellites are normally very small and difficult to spot. The two will station keep for a time and will appear as two moving stars in close proximity to one another.
Reentries are a real challenge in that the odds of actually spotting one is nearly impossible.
Amateur satellite observer groups have their own web sites and chat rooms online. There are also sites for downloading freeware and also for providing viewing angles, times and star charts at the click of a mouse. Compare your own experiences with those of others and get helpful advice from experts. They are responsible for providing accurate locations for some automobile navigation systems and for hand-held GPS units used by backpackers, surveyors, boaters, etc. This is an interesting specialized subordinate field of satellite watching.