How can I prevent incisions scars when I go for a round 2? (photo)

The revision implies that there is less fat than the first time, and scar tissue will make the surgery much more difficult on the surgeon.  The percentage of fat survival in the BBL the second time should be about the same.  You will have to find a surgeon who does mainly revisions and is capable of getting fat where others have not been able to do so. Liposuction scars are about 5 mm or less.  Also, you should consider the number of scars made for an area.  One surgeon may use 3 for liposuction of the abdomen, sides, and back and another may use 15.The scars from liposuction will continue to fade in most cases for at least one year.  I advise that scars not be exposed to sunlight for the first year due to risk for hyperpigmentation.  If the scars are elevated or irritated or there is exuberant scar tissue, injections of several items may be helpful.  Scar revision surgery can lessen the scar.  Other alternatives such as Intensed Pulsed Light (IPL) lasers (Fractora, Lumecca) may be beneficial. Laser may be reasonable after the initial phase of scar healing is complete at the 6 week mark in an uncomplicated case.  However, I usually recommend waiting longer, because time will usually be the best help, particularly in a good scar former.

Dear MissDrea,
scar prevention begins in the OR during the surgery when I meticulously close wounds in multiple layers in order to reduce tension and reduce scars width. I tape my incisions during the early postoperative period to reduce micromotions of the tissues so the incision can heal earlier. I also use compression garments and later Biocorneum gel.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

It is essentially impossible to avoid incisional scars for any surgery. Much of how scars heal depends upon the genetics of the patient. Notably, darker skin persons typically form darker scars. On the other hand, you do not seem to have much fat and seem to be naturally lean thus making you a poor candidate in general for BBL.  Instead of considering round 2 BBL, you may want to consider something more reliable and permanent such as buttock implants. Glad to be of help.

Unfortunately, you must cut the skin to make access points to do both the liposuction and the fat transfer in a BBL. When you cut the skin, there will be a scar 100% of the time. Scars differ depending on your genetics. Darker skin patients tend to scar thicker and darker. Asian patients typically do not scar "pretty". There are also many forms of scar therapy/lasers that you can purchase post op to help. Scars do fade over time and tend to look better at one year or longer after surgery. Finding a PS that chooses discrete placement of the scars really helps so that the majority of clothing/ swimmer hides the scars. 

Hi and welcome to our forum!
Unfortunately, any incision into the skin will cause a scar. In cosmetic surgery, we try to place scars in inconspicuous locations. The method of wound closure affects the appearance of a scar. The presence of postoperative infection affects a scar. Sun exposure to a healing scar may cause pigmentary change.  Scars may take 6-24 months to lose postoperative scar redness. Some individuals have a tendency toward thick scarring. Your surgeon may use the same incisions as in the previous procedure. 
We recommend intensive early wound management until the sites are sealed, later use of a moisturizer, a sunscreen when outdoors, application of silicone gel sheeting if a previous scar former, and tincture of time. 
Best wishes...

Your scars can't be excised to make them go away. In fact they would be much worse. If they are raised or thick silicone topical gel will help. Time is the most important thing to get rid of color in the scar. Two years post op is likely their final appearance. 

In order to transfer fat there has to be incisions. Fortunately, high definition VASER liposuction is less invasive than traditional techniques, so the scarring won't be as prominent.  A Skype or FaceTime consultation with a BBL specialist can help you get an accurate recommendation and pricing. 
Respectfully, 
Arian Mowlavi MD, FACS
Realself 100 Hall of Fame Inductee

in order to get to your fat the skin needs to be penetrated. To do this he will need an incision.Your second procedure can go through your old incisions there by not adding any new incisions or making your scars worse.I suggest your scars be managed with silicone sheeting, lightning creams and consider steroid injections. Scars change substantially over time and can take 18 months before they stop changing. There are certain things that are paramount for those who are prone to hyperpigmentation. For example scratching scars because they might itch after surgery can have a very negative long-term consequences.This is something you should be discussing with your provider during your postop visits.plastic surgeons are all well trained in skin healing.there’s no way to do liposuction or a fat transfer without creating some scar.Best, Mats Hagstrom MD