Wait until any above checks have been implemented or addressed before starting an amcheck--This is self explanatory; if an official check is yet to be implemented, you'd have to work off that anyways, and multiple stacked amchecks are hard to address properly. However, if another amchecker snipes you, feel free to post your check anyways--shit happens, and the slight inconvenience of having to look at two amchecks most certainly does not outweigh the loss of having two more eyes look at an analysis or just having all your hard work go to waste.
In a similar vein,
do not implement an unimplemented check and work on top of that--if the above check is an amcheck, you might be implementing suboptimal changes, and even if the above check is an official GP check, the writer should always have the chance to evaluate the changes made, and pre-implementing those checks would take that step out of the process.
Do not use placeholders--sadly, official checks do have priority over amchecks because they're sure to deliver, and amcheck placeholders slow down the process and would make the GP process near incomprehensible especially for new writers because of the additional red tape involved. HOWEVER, if an official GP member ends up sniping you, do not hesitate to contact them and ask if you can quickly finish your check / post your check anyway! After all, the more eyes looking at an analysis the better, and pretty much no one of us would mind waiting ten minutes longer.
Please, please,
do not actively discourage writers from implementing your changes until they've been officially approved--the more eyes that look over an analysis the better, and we sadly do not have the time to look over everything, potentially causing any good changes you made to go to waste. However, obviously feel free to point out to the writer that the quality of your check is not guaranteed, and naturally writers should use their good judgment when implementing amchecks--blindly implementing a subpar check, especially after a first official one has already taken place, wouldn't be helpful. It's just the "pls no implement" notes that we don't like seeing.
Try to exercise some restraint tagging your GP mentor to look over every single one of your checks--Again, this is for bottleneck reasons. A note "tagging
P Squared for a check" might end up discouraging other GP members from looking over your check, and your GP mentor might not have time to look it over. However, naturally you should be able to ask someone to look your stuff over, and if your GP mentor promised they'll get to it quickly, there's no problem--as long as it doesn't end up sitting.
Do not include copypastes--official GP members shouldn't do this either (except in exceptional circumstances, like right before deadlines in Smogon's Flying Press or if the writer's computer is broken) because this discourages the writers from evaluating their changes and effectively puts GP in control of the analysis, even though GP has no authority over the content, and we're only human, meaning errors might slip through! This goes double for amchecks, because those might include subpar GP changes as well.