I wish I had a pound for every time someone has asked me that question and that way I'd probably make more money than I've ever lost by posting goods before cheques clear - or don't clear as the case might be!
Bounced cheques can be a problem, especially for new eBay sellers who don't want to celebrate their first few sales only to find the cheques bounce for goods that have already been sent to winning bidders.
Another problem for newcomers is fearing negative feedback for not delivering goods immediately after payment arrives, even though cheques take up to seven days to clear (or to bounce!)
Thankfully, there are ways round the problem and I can honestly say I invariably send goods before payment clears and I've only ever been let down twice! For tiny amounts!
My view is that most people are honest, few will bounce cheques and for small amounts (less than £20 in my books) I always send the goods without clearing payment first. The same goes for payments awaiting clearance through PayPal.
My philosophy has always been that it's not worth making the honest majority wait for their goods just because a tiny few payments might be dishonoured. You need to keep your good customers happy and tempt them to buy from you again and nothing works better than fulfilling orders fast and trusting them to honour their side of the bargain.
That said, if a lot of money is involved or the buyer looks 'iffy', I break my own rule and let payment clear first.
With experience these are the rules I apply which you are free to copy in your business:
* Check buyer feedback, look for high feedback scores from other sellers, search for comments indicating payment disputes.
* Risk low amounts to new buyers but not if feedback already indicates a problem customer. For example, I would never send goods without clearing payment for anyone with low feedback and several derogatory comments made by sellers. Be aware, however, no matter how dishonest the buyer and no matter how disgruntled the seller, the seller always has to leave positive feedback or no feedback at all for customers, both criminal and honest. But you can sometimes spot warning messages made by sellers along with their forced positive feedback.
* Decide a maximum acceptable sum beyond which you will let all monies clear before sending the goods. I use £20 but I will go much higher for buyers with good feedback who have been registered on eBay for more than a few months and for anyone with whom I have already had a trouble-free transaction.
* Bear in mind banks charge you when payment fails, unlike PayPal where you won't be charged. I recommend PayPal for all your transactions.
* There is one time I don’t clear cheques before sending the goods. It's when someone buys and before the cheque arrives that person begins hassling me about delivery times or, worse still, threatens negative feedback if I don't get the product to them fast. In my experience payment from people like that has always failed.