For girls asking about shoes: For ODs there can be a little more flexibility, however it is recommended that shoes have heels (I think this excludes wedges, not sure), closed toe, no ankle straps and colour that matches your suit.
For the FI as well as the pictures you will have to submit, this is more strict... As for tan shoes, well, I guess they could be ok if they match your suit and fill in all the other requirements but black ones are the 'safest' option. You could always try the tan ones for the OD and then maybe switch to the others.
Mine are like this:
Not the best looking in town, but comfortable, classic, sober and cabin-crew-like.