I've noticed that the price difference between
MtGox and
BTC-e is often greater than 7%. But it takes only ~3% to transfer funds from MtGox to Btc-e.
So you can sell bitcoins for USD at MtGox, transfer funds to BTC-e and buy cheaper bitcoins there thus making ~3% with minimal risks.
The easy way of transferring funds from MtGox to Btc-e is
OKPay. I noticed that transfers may take from several minutes to couple days though, so it might be a good idea to make reserves of USD at BTC-e before placing your buy and sell orders.
Minimizing the interval between buys and sells you minimize your risks. Though it might be a good idea to make sure that sell order at MtGox executes before placing your buy order at btc-e since sometimes MtGox is really slow.
Why am I writing all this? Just hoping to get some passive income via OKPay's referral program. So if you find this advise useful, please use my link to get registered:
https://www.okpay.com/?rbp=arsenische