Ok, first the obvious:
unless you absolutely have to
don't take the test in June.
One thing I emphasize to all my students is that the LSAT is a skills/performance test, not a knowledge test. As with any other skill the only way to improve is through practice. If you put in enough intelligent practice you'll definitely do better. The key word there is enough
. That varies from person to person but is generally measured in months not weeks. Judging from what you said, that you've only taken 11 practice tests, that's not nearly enough to reach your potential. An optimal approach is one where you isolate and practice the different question types for each of the sections enough that you feel comfortable with the correct approach for each one, then isolate and do the sections so that you're comfortable with the sections, then do a group of tests with no time constraints, and finally have about 20-30 tests that you do under actual test conditions.
That being said, if you're committed to the June date and want to improve your logical reasoning score I'd recommend seeing which question types are giving you a hard time (if there are any others in addition to the ones you mentioned) and isolating and practicing those. Find an approach for them that yields good results, figure out why correct answers are correct and incorrect answers incorrect, and see if there's anything in particular that's causing you to get them wrong. Once you get comfortable with them then go back to doing full tests.
The basic approach to the arguments section is to have a very good understanding of what the premises and conclusion are (what exactly the argument's saying) before you go on to the choices. Judging by your error distribution (ie you're doing well on the reading comp) my guess is you're doing ok with that and the problem is most likely the specific types you mentioned plus the more difficult arguments questions that come towards the end of the passage and for which it doesn't seem to make sense why the correct choice is correct. Because of space constraints there isn't much that any of us tutors could write here regarding doing the assumption or parallel reasoning that isn't in the various prep materials out there. Obviously I recommend taking a look at my site: lsat.totaltestprep.net
, I have over 15 hours of video for the arguments section alone. In addition, the powerscore logical reasoning bible is pretty comprehensive and useful.
That's my .02, the other posts have good info so hopefully we've managed to help you a bit.