Originally Posted by Zorak

Additional caution: if you have a Flying Blue account, do not pull up the reservation at any point while logged in to that account, because in the past this had a high likelihood of poisoning the record with your FB number instead of your SkyMiles number, and if you don't realize this until it has been posted to FB already, it is near-impossible to get reversed so that you can credit it to DL (that being said there have been some success reports).

If you want to be really paranoid, look at your boarding passes and/or scan with a barcode reader and make sure the FQTV field shows your DL number and get it corrected at the gate otherwise.