Balance transfer advice

Hello fellow moneysavers,

Looking for a bit of advice on preparing for some BTs in late 2018 and early 2019 when my 0% deals end, which will be my first rollover of stoozed money. I have about £15,000 to roll over, currently split across two cards close to their limits, plus another £10,000 on other cards that will run on a bit longer. Credit score not currently great - between poor and fair on Experian, probs because I just got a charge card for a signup bonus - though has a bit of time to improve.

What’s the best tactic for rolling over the funds? Specially, I’m wondering:

- Do I apply for a bunch of cards at once hoping to get a few cards to cover the whole balance before the applications get through to my report and hit my score? Or will that not work/have a bad long-term effect?

- Is it worth paying my existing cards down a bit, e.g. to 75% utilisation on each down from 95%, to boost likelihood of getting new 0% cards?

- Should I cancel my charge card beforehand, since doing so won’t hurt my utilisation % (because it doesn’t have a disclosed limit) but will reduce my balance/number of accounts?

Any other tips on how to successfully roll the money over would be appreciated!

Thanks very much for any advice.