Paris by yourself

If you're looking for traditional stuff: Eifel tower, peniches, arc de triomphe, etc.

If you're looking for sthg different, try the cinema en plein air in Boulogne's Parc de Rotschild

If you can read french, try this: http://en.parisinfo.com/sortir_a_paris/

I've been to Paris in July last year. If you like clubs, dancebars etc..

Paris has many to offer. Just take a walk by the seine and choose.

I guess I shouldn't add nothing on Cafes. 

Go on an organised city tour - then you can see all the highlights but still feel safe - plus, chances are you'll get chatting to others on the tour and can socialise later.

Several of the tour companies and tourist organisations will organise walking tours of smaller parts of the city - these are good value

Otherwise - head for the Marais district, pick a good cafe with a table outside, order a good bottle of wine and sit back to watch the world go by ..... ... heaven !