@Brandi Agree with others - don't worry about mug betting or reloads. Focus on getting all the sign ups done and withdraw from the bookies straight away to put it into your exchange. Many of the bookies on sign ups you won't touch again as they never have reloads so don't worry about withdrawing.
Also I wouldn't join the free bet clubs right after opening your account, even if you get an invitation. A friend of mine joined the Sky one after getting an invite right after opening the account and was gubbed straight way. The ongoing weekly offers are great profit, so if you wait for a couple of months and keep placing bets every week before you join, it will increase your chances of more money longer term.
The accounts to start mugging as soon as you have the bankroll are - Sky, Coral, Will Hill and Paddy Power.
Also I would use Smarkets not Betfair - only 2% commission so saves a bit extra money.
Also if you're doing multiple offers at once, try to use the same game. Eg if you place a qualifier on Man U v Chelsea, Man Utd to win, place your free bet on the draw (if it's a decent match). That way you save on commission, can be as much as 50p per match which really adds up over time. It also means you use less liability.
FINALLY - Don't forget to check
Top Cashback... you get cash back on top of the signup offers, you can make several hundred extra by doing that!