Getting another publication out

People talk about the "difficult second album". It's the same with books. The follow-up to the debut book shows whether the first was a fluke, and whether the writer has any material left after having printed the collected best work of their life so far. I have 2 book[lets] to follow up - one poetry, the other prose - so my situation's doubly tricky. Two reasonable guidelines I've heard are

• Wait until you have enough material - there's no rush
• Wait until you've marketed and sold your earlier publications

In my case it's not clear that either guideline's been met. All the same, here are some possible future publications

• A 2nd poetry pamphlet - Less mainstream than my first. I've already sent to publishers and pamphlet competitions. Got close once or twice.
• A themed poetry pamphlet - Wordplay. Already sent to pamphlet competitions without success.
• A poetry book - using a few poems from my first pamphlet along with material from the above pamphlets. Never sent out.
• A 2nd story book - rejected once. It includes several previously published pieces, plus some prizewinners - about £300 worth of stories. More varied than my first book - in particular there are more micro-fictions.
• A prose book of pieces less than 1000 words long - never sent out. A dozen or so of the pieces have already been published, earning about £80.

I can pursue the publication of some of these in parallel. However, none of them is marketing gold, and competition from creative writing graduates and poets overseas grows more intense. The book need to be headlined by some more successful pieces. My plan in 2013 was to get some prose competition successes to strengthen the credentials of the 2nd story book, while placing poems in a rather higher league of magazines than I'd previously appeared in. No success. I'm trying the same scheme this year, with more emphasis on short prose. I've had some success, but not enough yet. So I'll wait.