a. the first photo should be a clear and well lit shot of the right-hand side of the bike. Ideally it should be sunlit or good incandescent or LED lighting. Avoid fluorescent tube lighting at all costs.
b. the bike should be clean-ish. Doesn't have to be concours level but we need to see the details and small features.
c. Show the whole bike, not just the frame.
d. high resolution - let us zoom in. The SE limit is 2 Mbytes on an uploaded photo. If that's not enough, upload your photo directly to http://Imgur.com/ and share the link.
e. Right-way up! Don't send in photos of the bike lying in a heap - try and get a view point that equates to about 2~3 metres from the bike, equidistant between wheel axles, and at a height somewhere even with the saddle or top tube.
f. Don't care about valve angles and crank angles, though trying to leave text visible is helpful.
Here's a workable photo - a plain background would have helped.
You can read off that its a shimano 105 groupset with dual pivot rim brakes and brifters, so the mechanicals are decades newer than the frame.
Another good photo from a successful ID question at Identify old bicycle w/locking steering column? Yes its inside, but the image is clear and well lit.
Not terrible but not great photos for ID purposes:
from Looking for help identifying my newest addition
Pretty awful photo for ID purposes (though to be fair this question was somewhat focused on the logo visible)
from What kind of bike is this? Can anyone tell by the logo?
Subsequent photos should zoom in on points of interest - what about this bike might be unique enough to promote recognition? Standard things would include
- Head badge or logo
- Any decals anywhere on the bike
- Strange things like writing or emblems in the frame
- Odd dropouts, front or rear
- Odd seat stay attachment to the seat tube
- Sometimes the fork crown can be distinctive
This question has some great examples of closeups on useful areas, but even so still remains without a confirmed identification. Name that frame! (Likely Japanese, likely made in 1986, with known serial number, likely a Bianchi)
Component close ups might help with dating, but often the components are used on many different bikes from different assemblers, and they can be changed after purchase. So a bike with "Shimano" on it is not a lot of help.