Paypal is the most secure way to send/receive payments... it's best for both the buyer and the seller. Some people here on ECF use postal money orders, but those are people that have been around the site for a while and are trusted. Are you the buyer or the seller? If you're the seller and you absolutely can't/wont use paypal, make sure you have the money in your hand before you ship anything out... If you're the buyer, then be certain that the person to whom you're sending the "other means of payment" is trustworthy...
As far as shipping, USPS has served me well for a while... make sure it's packed well and if it's a big-ticket item, you may want to consider insuring it...
hope that helps!