Once you clear the Heide Tower of Flame, dropping a sign near either of the boss entrances and just farming the statues is a descent way to get summons. I spent a couple hours just doing that and managed to get like 20 tokens of fidelity for the blue covenant. The area is easily accessible and lots of people want help on those fights for whatever reason. The Old Dragonrider will net you something like 5k souls per assist. Sentinels and Skeleton Lords are two other good places to drop signs if you want to get assists, once you clear the shortcut paths to both places. The Huntsman's Copse is someplace you will end up backtracking to farm poison cures, anyhow, since you need shit tons for the poison area.
Copse is also a good place to mess around if you want to get invaded, it seems. I have been invaded there several times, but mostly by clearly twinked idiots who built optimized mele rape characters for this purpose that are deliberately under leveled. I am no PvP god by any means, but I have yet to be ganked by these people. I mostly just either get on some hard to reach platform in the waterfall area or go wait on a narrow bridge. None of these guys seem to have any ranged offense and I have killed at least three of them by rolling in close and shield bashing them off a cliff when they are trying to close the gap with me as I soul arrow spam them. Like I said, mostly twinked out morons, which is fine because I have never enjoyed the pvp aspect of this game, really.