Only order 1 item per order - multiple item shipments are often held for weeks or months due to 1 item being out of stock. They will not send a notice when this happens, they just wait for you to figure it out. Check the website often for updates on your order. The "ETA" they give you is in no means set in stone - it can and will be extended several times.
Track your "cancellations" - if you cancel an order or part of an order they will not always send you a refund. It is up to you to make sure you get your money back.
Don't bother with tech questions - I've asked several questions about products and had to send repeated reminders for weeks only to get an answer that really has nothing to do with the original question.
Check your items closely when they arrive - I have had very few items that did not work, but several wrong items sent. The back and forth to rectify the situation is ridiculous, and the first suggestion they offer is just to credit you the difference between the item ordered and the item sent. However if I can't use the item they sent why would I want to pay for it?
These are just of the few things I've learned. Granted, they have many good prices, but the money saved may or may not be worth the hassle to you. Some items I have ONLY found here, so I keep previous experiences in mind. I also NEVER order something I really need from Fasttech.