From the first stage of your work - perhaps when you were asked to devise an 'identity sheet' on which to do your project - you will have been creating ideas.  Some aspects of some ideas will be better than others and some of the ideas will lend themselves more to changes and improvements.  Since you are the 'designer' you will need to point out what is good and what might be improved and this represents the start
of the choosing process.  The first addition will be to identify each idea with a letter and add a panel of comments on another sheet or alongside the first sketches.

An alternative way of showing what you think about the ideas you create would be to write a short paragraph about each of these ideas - analysing the best features and the reasons why any particular idea might be taken on to the next stage.

Once you have clearly made your choice the chosen idea will need to be taken on to the next stage for
development  …...

Experiment with colour changes and small differences with shape and line qualities.  Make your work look great.  Market research can help choose from this next stage and finally a chosen idea needs to be presented in a pictorial presentation - an isometric, an oblique or anything else you might choose - Perhaps an exploded drawing too if there are parts to fit together and it is important that the viewer understands how things are going to work..