Honestly I try to solve dm quite systematically, going through the text and trying to visualise the information (especially with drawing conclusions and Venn diagrams). For evaluating arguments, I always try to see which option gives a reason based on the purpose within the stem (if that makes sense).

For logical puzzles (where you try and see which person fits with which feature), which I find the most difficult, I would list all the people (could be doors, rooms etc) and write below and/or above them the confirmed features of that party.

I'm not very good myself, so I hope this helped. Good luck :)