If you have worked the "real world" of financial and budget management you are probably one of the very few parish councillors that has relevant and appropriate experience in a world that appears to be dominated by the well intentioned (I'll be generous) but ill equipped.
Just take all of your personal experience and introduce it to the PC.
From experience, I would suggest you might receive resentment, resistance and reluctance to adopt procedures that are alien to the dinosaurs that have "always done it this way" but you have to fight through that with simple logic and demonstrable example.
I joined a PC in the June of year 1 and by Jan of year 2 had provided the YTD cost of grounds maintenance plus anticipated costs to end FY - figures that NOT A SINGLE COUNCILLOR had previously any knowledge of! I then wrote, presented and validated a outsourcing contract which "should" have reduced the annual costs by 50% and generated income from capital asset sales.
Of course it didn't work out that way because the clerk and the chair let the contract in a secret meeting (which I gate crashed) and in violation of the delegated authority from the PC since the contractor did NOT satisfy the minimum requirements for award of contract.
It then took several years before the capital assets were sold having devalued in the shed during the inactivity, the contract which originally specified 3 football pitches was amended by the PC to uplift to 3 football pitches - at an additional cost even though 3 were already specified.
I'd resigned by this time and sat back watching the comedy unfold.
During the process of demanding answers to questions relating to costs for grounds maintenance which had previously been absolutely refused by the clerk (who, incidentally, was being paid to cut the football pitches ) that clerk - of 20+ years employment - claimed to be "intimidated" by the questioning and "resigned" threatening an industrial tribunal (sound familiar to anyone?) The threat of industrial tribunal mysteriously evaporated when countered with the realisation that a fraud investigation would be initiated.... The chair + 1 councillor also resigned.
The moral of the story - bring your own experience to the table, in a professional and competent PC others will recognise the addition of skills they may not have and welcome the improvement.
In reality, what will probably happen is that dyed in the wool "we've always done it like that", resistant to change dinosaurs will see you as a threat to their existence and rally against you.