One side of my nose is wider, what the best solution to fix it? (Photo)

Hi, Excersizes won't help. Sometimes selective injections can help even out a crooked nose, but in your case, Rhinoplasty would be the best option. Best Regards,Dr. Lane Smith Board Certified Plastic Surgeon Las Vegas / Henderson Nevada 

In the nose structure, the most important part is the base and septum. If the septum is deviated, the deviation is more prominent after the nose is augmented. 
From the pictures, although it is not very clear, it seems that your nose asymmetry is due to septal deviation. After a thorough examination of the nose condition with endoscope, rhinoplasty with septal deviation correction would help you reach the symmetry of your nose. 

A rhinplasty to narrow your nasal bridge would be the best option.  There are no exercises or injections that can correct this. 

Based on this photo is looks that full rhinoplasty with nose reduction would be good procedure for you; this will include asymmetric reduction of nose width and height. In-person evaluation in necessary to decide about more accurate plan of correction. 3D stimulation software, like one we use in our practice (Crisalix), may help communication between patient and surgeon to create appropriate working model. Good luck.

Click on the "Learn more" link, just below my response, or go here:
FacialSurgery.com/RealSelf/RealSelf_Breezee123.html
I made a computer morph of your nose, and an animation of the morph, to show the changes that are possible for your nose in truly expert hands.
I narrowed that left side, but also the right side, and I narrowed the tip as well. The woman in the short video that I posted with this answer had the tip of her nose narrowed in a rhinoplasty.
Your tip cartilages are strong, so we can see the outline of the edges of the cartilages, and the little dent between them. I didn't want to go crazy making to too narrow -- didn't want to maybe draw something that's not possible with real surgery. Probably you'll see the changes best in the animation.
You only posted that frontal view, but often, when the nose is wide, it's the three-quarter views, like the pictured woman in the video, where the width is most noticeable.
You should understand that the changes I demonstrated in the morph require advanced techniques, techniques that most plastic surgeons cannot handle.  Be sure to read the section in the "Learn more" link on how to stay out of trouble while searching for a rhinoplasty surgeon. Rhinoplasty is an exquisitely difficult operation to get right, and you should only have surgery if you are able to make yourself very confident in your surgeon's skills. Read that page very carefully. Most plastic surgeons are quite poor at this operation, and I believe my advice will go a long way toward keeping you safe.
I'd love to hear what you think of the morph. Did it seem to address your main concerns? I could modify the morph to your taste if you wish. Frankly, it's likely that the bridge can be narrowed more than I showed.
Your nose is also a good example of why computer imaging is mandatory in rhinoplasty. You need to know exactly what the surgeon is planning to accomplish -- what features he thinks he can change, and by how much he thinks he can change them. When you see his goals, you'll know whether he has an eye for an attractive nose, and whether he shares your opinion of what constitutes an attractive nose. You'll also know whether the changes he proposes are enough to be meaningful to you, and whether he understands your wishes enough to address all of your priorities. But remember, you're not hiring him for his skills with the computer. The doctor must then show you his before and after photos to prove that he can actually accomplish what he draws on the computer.
In your case in particular, you need to find a surgeon who understands all of the issues I mentioned, and how they fit together, and who can actually accomplish them in surgery. 
Finally, at the *very* bottom of the "Learn more" page is a link to instructions on taking and sending photos that are comprehensive and useful for an online consultation like this, in case you'd like a more complete evaluation.

Any wide nose can be narrowed by adjusting the bones an cartilages. If the bones are uneven, which they often are, one side bone is moved in more than the other side to achieve more symmetry.Your nose is wide all across, more on the left than the right, and it can be narrowed to match the rest of your face. This asymmetry extends to your nostrils and the tip of your nose. You would benefit from the expertise of an experienced plastic surgeon.

You need examination to answer this question.  Narrowing the nasal bridge usually requires breaking the bones and reshaping the cartilages.  cartilage removal may be needed as well. If your nose is wider on one side this may be due to a twist or deviation.  I don't think exercise or injections are likely to help you I am afraid.

A rhinoplasty procedure can accomplish narrowing the nasal bridge line and tip. Injections would only make the nose bigger, not smaller. Exercises will be of no benefit to the muscles in the nose. For many examples of narrowing a wide nose with closed rhinoplasty, please see the link and the video below