First, warm up!

If you're going to spend a lot of time playing guitar, then warming up is really important, especially in colder seasons. Of course, you should warm up every time you would like to practice guitar. But if your fingers are going to do extra work on that specific day, you should take the time to warm-up your hands, stretch your fingers and get some blood flowing through them.
Then, when your hands are warmed up, start working on the things you want to work on that day – slowly. Don't rush and try to play at your top speed, because your fingers will tire soon, and you won't be able to practice much that way. Start slowly and work your speed up.
 

Practice like you would every »normal« day
Do you have a practice routine? Stick to it. Do your daily routine, however long that is. Don't stretch the timeslots you have for each practising item yet (e.g. technique, scales, arpeggios, riffs …). Practice the same amount as you would on a normal day.
Then when you finish, you can start again and repeat the routine. That way your brain has some time to reset and get back in the learning mode. Don't get lost in practising a single lick for too long, because doing that will only waste your time and energy. Your brain wants variety and it learns best that way.

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Take breaks
After you've done a fair amount of practice your hands will feel a lot more synchronized. While that feels great, don't go on and play for hours at once. Take a break and put your brain and fingers to rest a bit. Cut your practice in multiple sessions of 40 minutes. If you have time off, feel free to make some coffee between sessions. If you are busy, do some other stuff, be active. You can even do some vocal exercises if you aspire to develop your voice as well.
Practicing too much in one piece will cause fatigue and your fingers will feel tired. And, as we mentioned before, your brain needs a reset from time to time. Doing that will cause a much more productive practice time.

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Be creative
After you've done the heavy lifting, feel free to jam with looper or over a backing track. This is a good way to work on your creativity or to develop new musical ideas if you aspire to write music.
Work on your songwriting. The best time to practice or actually do songwriting is when you have more time and your hands are ready to play what your head wants to hear.
Open Guitar Pro or a DAW you are using and start by writing down a single musical idea. Then use the remaining time to play with it and develop it. Add drum beats to it or add bass. Harmonize it, play it over different chords. Do with it whatever you want.
Want to write vocal parts as well? Start by writing down the first verse that comes to your mind and try to sing it over the instrumental you've created.
Don't judge the ideas at first. Put them out as fast as you can. One idea will lead to another, and then another and so on. Remember, you will always have time in the future to further work on the ideas if you want. The key here is to work with a few ideas and learn to manipulate them. This is far more valuable than the sole process of creating new ideas. And it can be really fun to play around with just a few notes
To summarize the article here are some keywords: start slowly, give your brain variety, be creative and don't forget to have fun in the process. This is how I personally would do my Sundays. :)

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