I've posted this info over and over again, and people still ask me the same question. So here it is in a prominent spot.

Does your shot taste balanced; are the sweetness, acidity, and roasty flavors in proportion?

• If the balance of the shot is good, but the flavors are not to your liking, you need to change coffee.
• If the flavors are to your liking, but their balance is wrong, with the shot tasting too bland, too in your face, too sour, or too bitter, you can fix it by changing dose and grind.

How to adjust dose and grind to fix the balance for most coffees

• If the coffee tastes too bland, the caramels and sugars are masking the flavors. Increase the dose, and coarsen the grind to keep the flow the same. This will reduce the proportion of sugars, while keeping the acid bitter balance the same.
• If the coffee tastes aggressive, you need more caramels and sugars, less flavors. Decrease the dose, and make the grind finer to keep the flow the same. This will increase the proportion of sugars, while keeping the acid bitter balance the same.
• If the coffee is too bright, with lemon, fruit, apple, wine and other acidic flavors, keep the dose the same, make the grind finer, to lower the flow rate. Make a slower flowing, more ristretto shot. This will reduce the acidity relative to the bitterness.
• If the coffee is too bitter, with too much "bright bitter" flavors in lighter roasts, like toast, wood, or lemon peel, or "dark bitter" flavors, in darker roasts, like blackcurrant, clove, tobacco, smoky pine sap, or peat, keep the dose the same and make the grind coarser. Make a faster flowing, more lungo shot. This will increase the acidity relative to the bitterness

What you will need to do this

• You will need a scale that reads to 0.1 grams, and you will need to weigh doses to the nearest 0.1 grams
• For many scales, it is easier to remove the basket from the portafilter and weigh it alone.
• If you are starting out, it is useful to time shots and weigh them as they are being pulled. A normal double weighs about 35 grams and runs about 27 seconds, and ristretto about 20 grams and runs about 35 seconds, and a lungo about 50 grams and runs about 20 seconds.
• Lots of patience when starting out

It helps to understand your grinder. Typically, a 1.5 gram change in dose for doubles will require the same offset to the grind setting to keep the flow the same, regardless of the overall dose being used (the offset is basket dependent). My personal experience is that changes of about 1.5 grams dose creates the tweak from blah to right or from too much to right. I also find that a grind change that would compensate for about a 0.75 gram dose change has the effect of moving the flow from normal to fast, or from normal to slow.

These tricks will not usually work well with Sumatran, aged, or Robusta heavy coffees. They mostly work well with other coffees.