So let's start with the basics:
Write down every scrap of information you can as you learn it. Make sure you include the source of that information in case you need to go back and check at a later date.
If you've found it online I suggest keeping the web address somewhere safe, it can save hours of work retracing your steps.
Names.Not something you can take for granted. First off, you have to worry about spelling. There are, for example, around 14 different spellings of the name Mohammed - which if you think sounds pretty hard to trace wait until you hear there are 18 variations of the name Chantelle (in no particular order: Chantelle, Chantel, Chantal, Shantel, Shantelle, Seantel, Shauntelle, Shontelle, Shontal, Chantalle, Chawntelle, Chauntelle, Chantille, Chantielle, Chantell, Chantele, Chantalle).
Add to the this shortening of names. Jo could be Joanne, Jo-Anne, Josephine, Joan, Jocelyn etc etc.
Of course that is assuming that the name they go by is their first name. They may use a middle name instead of their first name. Surprisingly more common than it sounds (David Law, James McCartney or even William Pitt are some more famous examples - that's Jude, Paul and Brad(ley)).
Then you have street names, pseudonyms or nome de plumes (pen names) (think David Cornwall better known as John Le Carre); stage names (Michael Caine - Maurice Micklewhite), nicknames, avatars etc etc. It might even be an initial.
Surnames aren't particularly straight forward either. As well as the above you have to take in names changed by Deed Poll, married names, double barrelled names, and maiden names. Also re-marriages and, as above, misspellings.
Misspellings, even on public documents, are in far more common than you might believe. Keep this is mind especially when dealing with unusual names.
If you can get a middle name(s) it can also be useful in tracking people, especially those with common names. But remember many people drop them or simply don't use them on every document.
AgesA date of birth is a big help. Remember in the UK it is day, month year unlike the US where it is month, day, year. Failing that it will help to get even a rough description. Are you looking for someone in their 20s or in their 70s? However never forget people are not always as observant as they like to think they are. So don't rely on it entirely. It is not unknown - or rare - for an eyewitness to describe someone as a "young girl in her 20s" when in fact the person you are chasing is actually a woman in their 40s.
Again make sure you keep a note of any scraps of information that come your way. As we shall see later it can come in handy when making connections. And even if it later transpires the information is wrong it means you can cross off avenues you may have otherwise have wasted time on
In the next part we look at where you can start finding names.
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