In reply to Tamati: It's not hard.
On very, very overhanging routes you will need to work them on lead which is marginally more complicated. However that type of route will also have safe falls and probably be stamina fest so you should managed to boulder the moves from one bolt to the next pretty much onsight.
For all other routes the first thing you generally need to do is get a top-rope on the route. A clipstick makes this easier - plenty of descriptions online of how to use one.
Once you are in a position to properly 'work' the route having either stick clipped it or climbed it 'bolt to bolt', you should start at the top and then work down. You need to do three things:
- Work the moves
- Work the clips
- Work the rests
Unless the moves are between rests you should always aim to work overlapping sections. That may start with just 3-4 moves but you should be aiming to get to the stage you can do the entire route in 2-3 overlapping sections. You generally don't get much benefit from trying to work the entire route on top-rope; it will just exhaust you and you will need to spent more time resting than if you do shorter sections.
Rest on the rope frequently and don't spend too long on the route before lowering to the ground for a proper rest.
Once you know how to climb all the moves, exactly where and how you will make all the clips (extending any quickdraws if required) and you know exactly where and how you will rest or shake out, you are then in a position to go for the redpoint.
If you fail on a redpoint attempt having given it 100% effort (rather than having fluffed a move/clip low down), there is one key piece of advice: rest, rest, rest some more and rest a bit more before trying it again.
HTH