Lens Filter Holder?

1. If possible I never put any glass between my lens and the sublect. You will find plenty of pros think like this.

2. UV and circular polarizor are my most used - if at all - these I prefer as screw on type. Can be very expensive on big lenses.

3. Cokin P system works well for those that use it a lot - mostly I use this for landscape work but I hate carrying all the gear and also they are expensive. Mostly I use this for ND filters as I can stack them.