First to first - very important is day time and weather when you want take your photos. Best day for you photoshoots is gray, cloudy day, when you have flat light every where and no shadows.
This is mainly important for vegetation textures as trees bush and of course buildings. Because you never had hard, dark shadows and what is important blue (or sometime magenta) aureole around you textures. It will avoid so much hard work after in post processing and save you time.
Next important thing is composition of yours photos, especially when you must take your buildings photos in narrow street and don't have good distance from buildings or others objects. You always will have lens distortion and perspective distortion. Last it's not very critical if you will take right way to do that. In short distance you cant avoid that. But must keep in mind that perspective in one direction, finally, makes you photo less twice! Look in picture.
VegetationOne important thing there is day time. Is the same, as I write before. Best day - cloudy day.
In first look, sunny without clouds is good, but if you want save a lot time to tweak your texture, better avoid this. Next important things, try found "clear area" angle of you shots, behind of tree, it will help you fast cut out process in photo editing program... And last, try found trees or objeckts, which does not have a unique feature. Items with a unique feature, always catches in the eye. And the next time sight of it, you think to yourself - oh, I already saw him. Its the samas as reapeting, so try avoid it...
Now about textures for vegetation. "Low poly" tree model must have 3 faces, so its required three different face of your trees or grass models. If you used 2 crossed between you never avoid "mirror effect" in you final textured model and usually its not good. You always need mask its from kamera, take lot time in future... What I should do? Faster way - is after you finish cut out main tree, just copy all sides in others two layers (in your photo editor. I used Photoshop, but possible it did in others free programs: Gimp, Krita and so on).
Used all new layers in same direction, and just change height and width with transform tool. In same place, you must delete some parts, in some add new details (with stamp tool). Then compare new tree faces with original and tweek new if found mirrored places on them... In right and left direction used the same method.
Finally all looks like this and you have 3 different faces for your vegetation model. Yes some time you can make few photos from different, realtree, direction, but you always need cut out it. This required addition time, so its not good if you dont have it enough.
In new file make simple triangle and define it as new brush. In later picture you can see how prepare it to work. Easy and very effective.
Some times, you need to have nice and original grass or small bush photo, so this scheme will let you have good photo from place. It's easy and flexible in use and you can take it when walking...
Sorry my english is poor, but I hope these tips will helpful any way...