In comment to this (obiviously), I found the best way to get a bounty and increase the heat levels is to run the streets until you get to level 2. Then make a slow break for the golf course/ country club. Now make sure you have full nos beofre you enter the course, otherwise it's a waste of time from the start.
Make sure at least one pursuit car follows you in- three would be better.
Write off 3 to 5 cars takes you to level 3. As you race around the course, more cops will show up, so try and write off as many as you can as fast as you can- because they WILL build up and stop you. Doing this constantly will rush you through heat 4 to heat 5 in no time.WARNING; KEPP YOUR FINGER ON THE NOS BUTTON, BECAUSE OF RHINOS. however avoiding them will be easier, as you can drift, where they'll just flip and roll. Don't worry about your nos, cos you can go fast enough at certain spots which will top up the tanks.
You will meet cross and his full team at some point- often without warning. Try to kill them all off, and make a break for the city. Of course, someone from crosses team will catch you, but you should have all of the pursuit breakers intact fo good use.
I should tell you guys now, don't bother using the bus station trick- where you can drive on to that platform to avoid the cops. Unlike the regular cops, crosses team are wise, and can nab you that way. Use the pursuit breakers then hide-FAST!!!Try using the tunnels, stadiums, the prison, or really, realy well hiden side streets.