This cute "Crazy horse" one is from Accessorize which is owned by Monsoon, and now does 10% discount to NUS holders, handy! These attach easily to the zips and can be a really fun way to spice your bag up, they're also detachable which means that you can up-date the bag by using the charms and make it better for one season rather than another using them.
The other one is also quite dainty and very sweet too and again from Accessorize. I have found that they seem to be the best place to get bag accessories from honestly since they specialize a little bit more!
Scarves are another great way. Very chic too! Just tie them around the handle or if their long enough wind around and tie at each end. These are great for handbags and are especially beautiful on fabric bags! I really recommend them on handbags that are fabric based more than leather just because they look as if they should have been there when brought! When your buying the little scarves don't think around your neck scarves, think more of the silky ones that you get to put in your hair, they have great patterns, lovely texture and are the right length.
If you've got a pocket that you can hook your sunglasses onto then that can be a great way. If you don't often wear sunglasses then I recommend buying some cheap sunglasses in fun colours i.e. pink or turquoise, and popping them just onto the pocket, they'll give any bag a more sunny feel and if you really do need them then they are there! Voila! They'll just help give a little bit of a pop to your bag.