Trying to get into this but finding it hard,any tips on what to build, best units etc ?
Don't play the campaign.
Start off on a survival map 1 on the easiest settings.Don't rush build everything or try to advance up the tech to early.
Build archers and have them patrol around your expanding base. Always make sure you have plenty of food and energy.
Hordes will appear every so often, usually 20 days depending on difficulty so at least make sure you have plenty of archers and a wall or two between them.
NEVER assume your safe, the Z's will find a way in even if it's one lone Z so always keep an eye on your map.
The game is ******* annoying and you will die, often over and over... have fun !
Watch some YT videos/guides is the best bet for help.