[engineer]

Originally Posted by doublejd

My ex-boyfriend used to do it a lot ...

Looking for some advice, please????

Hope you're a female then . Otherwise you won't get any advice

Just joking... welcome to TDP

About your question - well I think every serious punter will agree with me - you SHOULD have accounts with more than one bookie. Sometimes the odds difference is significant and you have to take the best offer.
My advice is to open account with several bookies known as the best in the online betting world:
(these are the ones I prefer)

Bet365
Paddy Power
Expekt
bet-at-home

will hill
vcbet
10 bet
Sportingbet

And at least one betting exchange (betfair).

There are numerous web sites for odds comparison, I use the following
UEFA Champions League | NBA | BetBrain.com Sports Betting Odds | BetBrain.com :*
and
OddsOddsOdds.Com - get the best odds! // Quotenvergleich / Odds Comparison