In terms of strumming patterns, there are loads and they will always vary, but some typical ones to try
(ps. Every tip/rule regarding context can be broken with these, it's all personal preference):
D : Down
U :Up
- D DU U DU (Good for verses/choruses at slow to mid tempos)
- D DU D DU (Maiden style Gallop)
- D DU U DU U DU U DU (Good for verses/choruses at slow to mid tempos)
- D DUD D DUD (Triplet/Waltz feel - Great for Verses/choruses
- D D U U D D U (Wish You Were Here Style Pattern)
- D D DUD U UD DUDU (Green Day - Time Of Your Life style pattern)
In terms of building from a verse to a chorus you could have (depending on the build length):
- D D D D (x4) (Simple build up to a big chorus)
- DUD U U U UDUDU (More of a grandiose turn around into a chorus or even a verse repeat)
- D D D DU D D D DU, D D D D, D D D DU (Gallop style build)
More often than not though, you'll find good strumming patterns naturally occur through your exposure to different rhythmic ideas, the above examples are ways to get exposed to those ideas but when writing, usually you won't necessarily be conscious of the strumming directions, only the rhythm that you're trying to get across (It can be difficult to derive the exact rhythm from text etc)
Hope you can get use out of some of this!