Depending on the kit.....
If the extract is hopped (some canned extract) don't boil that portion.
If you have to steep grains, keep the temp in the 150-160 range, don't boil
Turn the flame off prior to mixing extract so it does't scortch
Don't fret about all the trub from the kettle going into the fermenter...it just looks gross

DO NOT TAKE YOUR EYES OFF BOILING WORT, especially if your kettle is more than 1/2 full of liquid.
Be patient waiting for fermentation to begin...it can take awhile. Keep you wort temp as close to 67-68F as possible during fermentation.
Wait at least a week after fermentation begins to worry about a FG reading.
RDWHAHB
Have a blast!!!!