The carry over option shouldn't be used, just exploit the random number generator, it will eventually give you a level you can do :) Also the achievements give you helpful bonuses for any new games, so just start on casual with a few of the MODs to make it easier and you will soon be able to start doing hardcore mode.
Made it to level 50 at last (on casual) using a Sheriff with a shotgun, gonna have a go on hardcore with a Noble as they get good bonuses - I found the key was to level up house and get minions asap. (@Shoat - their special power isn't using all weapons, its a bonus to accuracy/damage, the all weapons is just to let you chose what you want to use at the beginning)
@rydy - carry over mode just allows you to get a bit of extra money at the cost of not being able to get any achievements, you unlock the other 4 classes by getting to lvl 10 in each of the starter ones (see the museum for details)
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