How would you say....

Help please ^ ^
I just need to know it like if i was talking to a friend.

How would you say:
I forget to write sometimes also.

I forget to write sometimes also.
I am assuming that you wrote a letter/e-mail to a friend, then later you are writing another one as a follow-up.

If you mean "(In addition to something I mentioned already, there were) some other things I forgot to write."
- Hoka ni mo kakiwasureta koto ga atta yo.

Just in case, if you mean "(Like you forgot to write something), I, too, forgot to write something."
- Watashi mo kakiwasureta koto ga atta yo.

AK-san,

"sometimes", not "something".

Oh, sorry, I completely misread the post! Thank you, anonymous.

- I forget to write sometimes also.

So I guess you mean "I, too, forget to write (e-mails/letters) sometimes."
- Watashi mo tokidoki kakiwasureru yo.

But in this case, the real meaning would be more like "I too sometimes forget to write back/replies," right?
- Watashi mo tokidoki henji suru no wo wasureru yo. (I too sometimes forget to write back a reply.)
- Watashi mo tokidoki henji suru no wo wasuretari suru yo. (I too sometimes do things like forgetting to write back a reply.)