Well now I have written columns in Folwrite and Somer's Journals for nearly 20 years now. And before that I had a stint writing editorials for an Institution (techie ones not looney ones) magazine.
1) You can check yer facts till the cows come home but errors will happen.
2) What is plain obvious to you can be misconstrued by anyone and only when you go back with their mindset will the ambiguity shreik at you.
3) I love humour (particularly puns) and it was pointed-out by an editor who liked my stuff that she always told people to read it out loud - the jokes then rather fall into place. Beware the "aural" inferrences - unles you spell it out, meanings can fall on stoney ground.
4) Avoid too many me's & I's - the reader might think it is an ego trip rather than communication.
5) Good luck - and good judgement - and then you don't have to be apologetic.