Some tips about writing papers
How to write a paper?
1) Take your time, it’s worth it! Write, rewrite, try to get to the end of your question.
2) The introduction should be accessible (get someone to read it and give you feedback). State your theorem in the introduction. This is where you sell your paper to the reader, the editor, the referee,…
See also Dan Margalit's 13 commandments for writing papers.
How to advertise a paper?
1) Put it on the arXiv and on your website.
2) You can email it to people you think should be interested.
Where to submit it?
1) It can be difficult to pick the right type of journal. Ask for an advice. (For topologists, see also Dan Isaksen's list of journals with topologists on the editorial board.)
2) Don’t get too upset by a rejection!
3) Spread you papers on different journals.
How to answer a referee report?
1) Take it seriously!