I brew partial mash and I was wondering if anyone could provide me with good tips that might help me reach scores of 40s or better if possible.
Scores in the mid to high 30s are comparable to well-made commercial beer, and are often good enough to place or win. If you're consistently getting scores in that range, you're doing very well!
Scores in the low 40s are generally the highest that judges ever give out, and indicate truly astounding, world class beer. I describe any beer with a score of 45 or so as "the angels sing when you taste this beer." A hypothetical score of 50 would be "Choirs of angels sing, the heavens open, divine light shines down on the beer, the hand of God points down at it and a booming voice says, "That one!"

Look at the Commercial Calibration column in Zymurgy to see the sort of scores that Grand Master judges give to well-made commercial beers. That will give you a better idea of how judges score good beer.
Anyhow it seems like im missing the mark on the Flavor charecteristics, my score tend to avg between 10 and 12 out of 20.
So, look carefully at the judges' comments for Flavor and Overall Impression and tweak your recipe from there.
As a guess, you might be missing the sort of subtle sweet, grainy, bready pale malt flavors and aromas that good all-grain brewers can put into their beers. If you aren't doing it already, you might try doing a mini-mash of pale malts. A crock pot works pretty well for this, since it can be temperature controlled in roughly the ranges you need for mashing. Its only limits are that you can't put more than a couple pounds of grain into it and it's messy to get the liquor out of it.
Mash at higher temperatures to get a more dextrinous wort from your grains. Your malt extract will provide the fermentables you'd get from a lower temperature mash.
Practically, there's no reason to switch to all-grain when you're brewing most styles of beer, as long as you're using good quality, fresh malt extract and you've got your mini-mash and grain steeping techniques nailed.
Ways to improve your beer otherwise:
1. Be righteous about sanitation.
2. Only use pale malt extract and only use it to replace base malts used in all-grain recipes. Use mini-mashing and/or steeping to for other malts.
3. Make a yeast starter. Keep it at the right temperature. Pitch the proper amount of yeast for the style. Properly aerate your wort immediately after pitching your yeast.
4. Gain fine control over fermentation temperature. This doesn't necessarily mean a refrigerator or a chest freezer with a temperature controller on it. Depending on your house, your climate and the style of beer you're trying to brew, it could be as simple as putting your carboy in a temperature-controlled water bath - like a plastic trash with a fish-tank heater for a temperature control.
5. Chill your wort quickly. Immersion chiller good. Counterflow chiller better. Counterflow chiller running ice water from an immersion chiller set in a bucket of ice best. (short of a glycol-chilled heat exchanger like pro-brewers use).
6. Blend your beers. Make multiple batches with slight variations in technique and ingredients and blend them.
7. Practice. Don't skip around the style guidelines. Just brew one or two styles of beer until you've got them perfected. Then branch out. Try to identify and eliminate any sources of variation in your brewing set-up and ingredients as you go. Learn the quirks of your brewery and equipment.
8. Keep good notes. Otherwise, you're just guessing when you try to recreate a really good batch.