This is a mock up of a basic magazine front cover. It includes all the standard conventions of most magazine covers- the masthead, main image, headline, strapline, serveral cover lines and a barcode with the price, issue number. It also features a puff. This is like the caption of the magazine saying something like 'The world's number one magazine'.
The masthead would be at the top of the magazine in a large font which would be the same point size and font on every issue of the magazine. The puff would be underneath to the left of the masthead, slightly smaller but again would be the same on every issue.
Then the main image would cover the whole of the background of the magazine and would be of a celebrity or something featured in the magazine.
The headline will be near the centre of the magazine, although this could change depending on what the main picture is like. It would be slightly smaller than the headline, however larger than the other coverlines. It would also be bolder. The strapline will be directly underneath this, in slightly smaller point size, however in the same font so you know the two are related.
Finally the cover lines would be spread over the magazine appropriately according to the main picture and headline. These may be in different colours however would be in the same font and point size.