The Frontside 180 Ollie is the obvious next step after learning the straight ollie. Not only will having a controlled 180 ollie help you learn about landing tricks fakie (i.e backwards) but it will also give you the confidence and technique to move onto more technical variations of the basic 180 (frontside and backside kickflips etc).
Right, so a frontslide 180, for that you want to get your feet in pretty much the same position as you would do in an ollie, but your back foot wants to be more towards your heel edge. So you're using your toes on the back end of your board. When it gets left at a comfortable speed, when you're ready to do it, turn your front shoulder away from your board, front side.
Pop it, bring your back leg round to a 90 degree position.
When you're ready to land it, just let your legs follow round to your shoulder. You should land 180 and get ready to ride away fakie.
If you can go at a half a silent night bed, but it might be easier to do it with a small curb or over a little grate or something like that.