Learning guitar hurts. Any guitarist will tell you that. When you're starting out, you'll want to put as much time in as you can to nail the chords and scales you're learning. The downside is - the more time you spend practicing, the more your finger tips will hurt! Fortunately the pain does go away, and your finger tips will get used to holding down the strings, but here are some tips to help you avoid the soreness so that you can strum for as long as possible!
1. Don't press the strings too hard
When you're starting out, it's likely you'll be pressing the strings down harder than you need to. Next time you go to strum a chord, relax your fingers, and then press the strings hard enough so that the strings come in contact with the fretboard. When you strum the chord, all of the notes should ring out clearly. Loosen the pressure as much as you can while still being able to hear every note clearly. Keep practicing that and try to break your habit of pressing too hard.
2. Adjust your guitar's action
The "action" refers to the space between the fretboard and the strings on a guitar. A high action means the strings are far away from the fretboard. A low action means the strings are close to the fretboard. You want a lower action rather than a higher action, but you don't want an action too low that your strings don't ring out properly. The best thing to do is take your guitar to a guitar shop for a setup, and ask that they lower the action.
3. Use lighter gauge strings
Guitar strings come in different diameters - called gauges. A light gauge will be a smaller diameter, whereas a thick gauge will be a larger diameter. You will get a slightly different sound from lighter and thicker gauge strings. With lighter strings you'll find the strings easier to hold down and bend, but you will also find that you won't be able to de-tune your guitar very much. A thicker gauge set of strings will be harder to hold down, and harder to bend in standard tuning, but they're much more suited for de-tuning your guitar to lower tunings. A set of 9s is a good string gauge for when you're starting out.
Everyone who plays guitar has experienced sore fingers. Try to play little and often rather than practicing for hours when you're starting out. After a few weeks of regular playing, callouses will begin to form on your fingers and the soreness will no longer be an issue.