The first thing to bear in mind that dyslexia cannot be overcome; but if you are determined enough and have aptitude in certain areas you can certainly devise strategies to deal with it.
I have a dyslexic DD who is 13 and in year 9 at a comprehensive school who has been in the top class (of 9) since starting there. I would tend to agree with happygardening that self esteem is extremely difficult to address. DD is obviously as intelligent as her classmates but will do less well academically in most subjects at GCSE.
In general I would say to see what your child's strengths are and play to them. DD is very good at art and while I think she would have been an equally talented engineer (she can see in "3d"), I reluctantly now accept that she has lost confidence in her academic ability.
DD's school has a fantastic Sen dept, however some individual teachers have been less than helpful. While maths was her stronger subject on starting secondary, now it is English due to a fantastic talented supportive teacher and mediocre maths teachers.
Technology can help a bit - word processing is obviously easier than writing longhand but draws the attention of everyone else in the class!
I have also let the school put her through the trauma of an early MFL GCSE in year 9 - while with her private tutor's help she may scrape a B, her less hard working but equally intelligent classmates will walk away with A*s. She spends 90% of her time on the language to the detriment of her other subjects.
I have a step brother who is dyslexic who has a doctorate and a great job but who has never read a novel. He was lucky he was identified as very able in maths at a young age.
I often worry that DD is fairly culturally illiterate. She just cannot pick up the information that most people do from the media around them. She loves the theatre and opera (and has been lucky enough to perform in professional productions) but hates museums and (ironically) art galleries. She is quite musical but plays or sings from memory as she cannot sight read.
My elder DD is very academic and good at everything which is a hard act to live up to. My view for a long time was to be absolutely determined that DD2 would not let dyslexia stop her and do as well as her sister.
I have now said to her that grades at GCSE don't matter as long as she gets C or above, as that is all she needs for the art course she will probably end up doing. I do actually think that DD will be very successful at whatever she ends up doing because she is naturally talented and has a very attractive personality that people in general warm to.