Judging from the answer to this question, imported characters benefit by being able to start at level 30. What about freshly created, non-imported characters? Do they also start at level 30, or do they have to train their way up from level 1?
A newly created Shepard starts at Level 1.
Early levels go by very quickly however. For example, you'll be level 3 by the time you get off of Earth. Additionally, your opponents are scaled to your level throughout the game, so once you get past the first few levels, (where a lack of available skill points hampers your tactical options), you shouldn't have any particular problems being a low level character. It might make reaching level 60 in one play-through more than a bit problematic however.