The main thing with mines, particularly since they have blast radius upgrades, is to keep them far enough apart that they won't blow each other up if one gets set off but a stand clearing spinfusor shot. Also, putting them in sequence is a good idea, because two mine hits will outright kill any light.
I find that force fields are better used to draw fire and funnel people down the routes you want them to take, usually because those routes are full of mines. They also good in parts of the gen rooms because people will go through them without thinking, or inside other parts of your base to make people stop and kill them, potentially getting caught out by your team, or maybe they'll just walk through, and take the damage. I find that tactic particularly useful on Crossfire, because your ship/base is so big, you can put force fields inside and really mess up enemy movement, including the fly through cappers, without having your fields subjected to much long distance fire.
