Always choose suede or nubuck over polished leather as these materials are more likely to give in and stretch.
If you opt for leather, then ensure it is soft and has no stitching on the edge, especially when you are selecting sandals.
Great examples are Timberland Women's Los Angeles Wind Slingback Sandals and Clarks Rene Sienna.
If the stitching is present, it must be very thin without extra material layer in between, like in ECCO Shape 35 Block Slingback.
Also good soft leather shoes with invisible stiches are Clarks Trace Stitch along with ECCO Shape 65 Block Ankle S and ECCO Shape 35 Wedge Ankle.
The contemporary polyester and tech stretching materials are very good for wide feet as well.
Remember that your foot will sweat more in synthetic materials so opt for a shoe that is well ventilated by design.
The best examples of such shoes are Hush Puppies Labsky Elastic and KEEN Women's Uneek O2.
Look at you foot and determine the widest part.
If your widest part is across the inner side of your toe bones (Bunion syndrome), make sure your shoe shape is not constricted on the top: no T-strap or strap across the toes that lies exactly on top of your poking foot joint.
The top of the shoe box should contain elastic inserts for added comfort if the feet swell.
Your shoes must resemble slippers with an extra elevated sole, with a heel 1 cm to 3 cm (1 inch) max above the sole height under your toes.
Great examples are:
If your foot is more or less homogeneously wide without standing out joints on either side, opt for shoes that have round toe box, much rounder than a usual almond shape.
Don't forget that all shoes made of leather, suede and nubuck can be scratched to meet your exact needs.
Your can try to do it yourself using the shoe stretching spray, that you can find from Ecco, Salamander, UGG, Timberland or any other.
Do go to cobbler, shoemaster or shoe repair shop and ask them to stretch your shoes.
With professional equipment it is possible to stretch your shoes precisely where needed and up to 0,5 inch (1,5 cm).
Also try avoiding 100% synthetic socks and stockings in hot summer days, your feet will swell even more and can become itchy or feeling that hot burning sensation under your toes.
Go for short cotton, viscose, tencel socks or barefoot if possible.