Getting a roll back that is blank or filled with light leaks is a terrible experience. The odds of this when starting out are even higher due to inexperience with your camera, or loading film in general. In this post, I'll give you a few ways to be more confident in your film loading.
After getting your film leader in the take up spool, advance your lever a couple times to make sure it stays in. This may take up a bit of film, but generally the beginning of the roll isn't usable to begin with.
Keep your eyes on your rewind knob. This is important to watch because if when you advance your film it doesn't spin, this means it's detached from the take up spool and not truly advancing.
Check your film advance lever for tension when advancing. If it feels differently than when advancing an empty back, this is a good sign.
Let's say you really don't trust it your abilities. If you want to check, simply press the rewind release button on the bottom of your SLR and rewind using the knob on the top. If you feel tension, that's a good sign. You could then keep rewinding all the way until you feel the film pull out of the take up spool. Important note: don't rewind beyond this because your film will go all the way into the canister, which is a pain to fish out. Once your film is off the take up spool, you can respool it, and fire the number of frames you'd previously shot with your lens cap on to get back to where you left off.
There are many ways to double check your loading job. Though it may seem foreign and scary at first, over time this process becomes second nature. Though you may have issues the first few times, we all have to learn from our mistakes!