If you've taken the leap into the world of ordering hair extensions from an online vendor, there are few things you should do immediately upon receipt of the hair. You want to do these things sooner then later so if there is an issue you can make any returns or exchanges as soon as possible.
First and most importantly make sure you received what you ordered. Check what you received against the packing slip or invoice. Make sure that if you ordered curly that you revived curly. Also if you find any major faults or discrepancies take a few photos with a camera and enable the time and date stamp feature. This can help expedite any communication with the vendor as they can "see what your" talking about.
Measure ~ Measure the length of the hair. Take a tape measure and double check. (I couldn't find my cloth/soft tape measure in my sewing/art stuff so I broke out the real deal).
Curly and very wavy hair are measured when stretched.
Weigh ~ If you have a scale that measures ounces weigh the bundle(s) of hair to make sure that you received the amount that you ordered. I bought this food scale at IKEA for like $4.99, it's not supposed to be used for trade (its not an official scale), but it works. I adjusted the scale so it measures zero when the bowl is on top and empty, of course. I don't have time or the patience to do math equations so it's easier for me to know that the when the scale is on the bowl it is at zero.
Check for Nits ~ I said nits not lice! Most hair extensions hair come from 3rd world countries and sometimes 3rd world stuff happens in the hair world. This happens on occasion. Especially if your dealing with vendors oversees or a vendor here that might not take the extra steps to remove them prior to shipping. Lice are parasites and cannot survive on hair that isn't attached to a "host". Nits are just the shells. Yeah it's gross, but it's not the biggest deal. If your totally disgusted contact your vendor ASAP and make arrangements for an exchange. If your bold, contact the vendor to let them know, and break out your fine tooth comb and get the nits out.
Wash & Condition ~ This is one of the last steps of your "inspection" In most cases you cannot return the hair once "altered" meaning washed, installed, etc.. You really want to do this for sanitary reasons. Also see how the hair reacts to washing. If you ordered curly or wavy hair you should really see the curls/waves "pop" after washing.
Seal ~ Seal the wefts this step is optional. I made a tutorial here.
I hope that some of these tips help.