3D Printer are precision machines. A LOT has to go right for a print to be successful. You have (4) stepper motors working in harmony while melting and extruding plastic in the shape you desire.
One thing that many users over look is actually measuring your filament. Just because it says 1.75mm on the label doesn't mean the filament is actually 1.75mm! Most companies, at least reputable ones, will list a tolerance on the filament - generally +/- 0.02mm is acceptable.
How do you measure filament? When I open a new spool of filament I'll take (6) measurements and average them. I'll measure about 12" from the end of the filament with a set of quality digital calipers that are able to read to 0.01mm (such as these: Mitutoyo (Clone) Digital Calipers 150mm – The 3d MakerPlace) then rotate the calipers 90 degrees and measure at the same spot. Some filament won't be perfectly round so measuring the thickness twice in the same spot will catch if the filament is egg shaped. Next, I'll move up the filament another 12" and repeat the same process taking (2) measurements at the same spot 90 degrees offset from each other. Finally, I'll (2) more measurements another 12" up the filament. Once I have these measurements I can average them all together. If I'm within 1.73 - 1.77mm range I won't make any adjustments. If I'm lower than 1.73mm I'll increase flow, if I'm above 1.77mm I'll decrease flow.
Anytime I get a clog or a failed print that looks like there may have been an extrusion issue I'll measure the filament again to see if it changed. This is a vital step to understanding why prints fail! Happy 3D printing!