The best way to practice is a little each day, even 10 or 15 minutes! The key to success is not how long you practice but how often. A little each day is better than an hour on Monday and not picking it up till the end of the week. Keep it fun, keep it musical. I've had students tell me they were going to practice hours a day and I tell them to start with 15 minutes a day and gradually work up to more time if life allows. Make easy, attainable goals otherwise you're going to get frustrated. If you can, keep your guitar out of it's case where you can quickly grab it, having to get it out of it's case can be another obstacle to playing. Work it into your life a little at a time, don't make it a job! The students that I've seen have the most success are the ones that chip away at it, a little at a time. It takes time to master things, and it's important to understand how we learn something new. We always understand more than we are able to do. For instance, it might be easy to understand how to play a new chord, but playing it clearly and consistently might not happen for awhile. That's o.k.! Stay with it and you will be amazed at what you'll be able to play, usually in far less time than you imagined.
Encourage yourself and stay positive, the rewards are well worth it.