Universities are highly likely to give you an offer if you do amazingly well in the UKCAT or BMAT, so work hard and practice, practice, practice in order to attain high marks. This is a key factor in entrance, especially if other factors aren't so brilliant.
Look at your Personal Statement, something to improve on there, don't write about being passionate or I could really use this, because they know that since otherwise why are you applying? Talk about your medical interests and pursuits.
Work experience, contacts, networking will also drastically help for next time you re-apply, put yourself out there and get a recommendation from a doctor which will boost your application.
Never give up! It's a tough degree to get into, with 1 in 10 offered a place, so think about it in the way that if you only have 4 UCAS options, that's 60% people likely to miss out.