I know it sounds silly and way to simple to deserve any explaination, but that's exactly where it all goes wrong. One of the first things I learned was how important it is to properly measure flour esp. given that I am more of a "eyeball it" cook. The best way would be to use a scale and this in my opinion provides the best results. You can use a fancy Digital Scale but a simple one, like mine, works great as well.
But if you don't own a scale, then then obviously the next best thing would be to use measuring cups for dry ingredients and liquid measuring cup for the wet. Yes, you heard me right, two separate ones. This is how I go about measuring the flour for baking
Step 0: Though tempting, never scoop the flour right from the container into the measuring cup. It compacts the flour and packs in more flour than appropriate. Step 1: Fluff up the flour with a spoon. Step 2: Use the spoon to add in flour to your measuring cup.Its more like sprinkling the flour into the measuring cup. Step 3: Add right to the top. Step 4: Level it using a knife or any straight edged utensil. Step 5: Now use this leveled flour for your recipes. Here is a helpful chart which gives you the weights of different flours when measured properly. You can use this as a guideline if the recipe does not specify the amount in weights. This is the chart I use that's stuck to my fridge. I have only listed the flours that I have used until now.

Flour	Cups	Weight (grams) (rounded)	Weight (oz)
Almond Flour, toasted	1 cup	96	3.375
Amaranth flour	1 cup	103	3.625
All-purpose flour	1 cup	120	4.25
Barley flour	1 cup	113	4
Bread flour	1 cup	120	4.25
Buckwheat flour	1 cup	128	4.5
Cake flour	1 cup	113	4
Chickpea flour	1 cup	85	3
Flax flour	1/2 cup	50	1.75
Oat flour	1 cup	92	3.25
Potato flour	1/4 cup	46	1.625
Quinoa flour	1 cup	110	3.875
Rice Flour, White	1 cup	142	5
Rye, Pumpernickel	1 cup	106	3.75
Self-rising flour	1/3 cup	39	1.375
Sorghum flour	1 cup	138	4.875
Soy flour	1/4 cup	35	1.25
Spelt flour	1 cup	99	3.5
Tapioca flour or starch	1 cup	113	4
Teff flour	1 cup	135	4.75
Whole Wheat (traditional) flour	1 cup	113	4
Whole Wheat (white) flour	1 cup	113	4
Whole Wheat Pastry flour	1 cup	96	3.375

Reference: KingArthurFlour.com