ND filter advice required

hi this is my first post on the site and i would like some advice if possible.

I am new to photography and own a canon 650d with kit lens 18-55 & also the same lens in 55-250.I enjoy landscape photography and would like some advice on purchasing a square filter kit i.e cokin,kood, etc.

I have seen kits advertised by various manufacturers including some on amazon and ebay for very little money at all.Could someone please give me details on which filters etc to purchase for my needs.I dont want to go down the screw in type route.

Any advice will be most welcome

Regards Adrian