Sideboarding is very dependent on what cards are in your 75, and what deck you are playing against. Its not really different from other decks in that way with exception to how many cards you are taking out / bringing in for each MU. In general, you should board put cards that are bad or useless in a particular MU.
Against storm, the mirror and other fast decks I think its fairly common to do very light boarding. Basically just focus on taking out really bad cards, and bringing in some lands / 0 and 1 drops. For the most part though, your main deck should be built for these matchups. Outside of these MUs you can cut some of the cards that are there for speed and consistency, for instance:
Anti Storm/Dredge cards:
Leyline of the Void - This card is just not very good outside of these MUs and can easily be boarded out.
Mindbreak Trap - Again this has some impact on other MUs, but it really is only played for the Storm MU. Feel free to board it out if your Blue count is sufficient for Force without it.
Fatestitcher - This only works with mana, active bazaar + GY. This is too perfect of a scenario to be realistic for Games 2/3.
Dread return targets - These cards are generally unusable unless your opponent has no hate.
Lion's Eye Diamond - You almost never want to pitch your whole hand in games 2/3 and the mana is more of just a biproduct.
Ect. - Speed cards are for G1, and MUs where you need to win quickly. They are easy cuts.
Serum Powder - This card helps with consistency, but in games 2/3 you are looking for higher variance wins and improved top decks.
Trim copies of dredgers, dread return, and therapy - These are tough cuts, but some cards have to be cut and builds often run more of these cards than are necessarily needed.
Against specifically slower control decks, workshops, fish, and other aggro. Disruption is less important in these matches, and you need to make sure your GY is lethal enough since they can actually fight back against weaker on board presences. Cards that I take out:
Cabal Therapy - Trading a creature for a card from your opponents hand is not often a good exchange in these MUs.
Counterspells / Unmask - These cards can be very hit or miss and if you have other ways to remove hate, Id considering cutting them down.