@chitty talked about this abit in his post on the different voting strategies:

Some dolphins follow whales and try to vote just before them, in my opinion that strategy is not adding any value to steemit curation system; on the contrary it is giving the whales even more curation responsibility.

The best way a dolphin can make some curation SP is by reading the “new” category and voting on good posts that they think will likely become popular, depending on their SP they should vote in the 10-25 min range. By being the firsts to vote they can make a couple of SP per post and also feature good content on the “hot” list so that the whales can come in and give their votes to already “pre-approved” content.