If pricing is not your thing may a price/job calculator is the way forward, it needs all the specifics though to make it accurate....
Yeah, agreed - pricing can be the bane of any job. And there are so many hiddens initially, it's easier to get it wrong than right.
Best, easiest thing to do is to build a basic spread sheet, listing everything, and with your mark ups already put in - so you can see the job build up in front of you.
For us, We put in materials at list price, then a labour time per "item" - so it calculates if we have ten of an item, or one, or three.....and give a line total of unit price, and labour time.
Then we apply our mark up to the total materials price at the bottom.
Then we add a margin for fixings, and other misc items.
Our labour rate takes account of direct overheads, and is set accordingly. The sheet then adds in the total labour * the labour rate per hour.
Finally, we have the sales total - but our sheet also calculates GM and GP for us too - which is transferred into another sheet automatically, against which I monitor our quotes, and margins, etc....
We can also quote buy-ins as part of the sheet - ground works, specialist commissioning, project management - stuff we buy in complete, that we don't do ourselves as such. And finally it can calculate sales commission - which we pay on profit, not on invoice value (hard to get your head round at times).
It's not a pretty sheet, but as a build up sheet it does what we need it to.
Critical calculations for us are labour rate - overheads - we need to know how much profit we make on our labour (or not). In simple terms, if our overheads are say £25 per hour - we need a labour rate in excess of that, which is generally set at a level and left there - say for this discussion, £35.
Margins are then calculated on the elements of the price that are not cost of goods - or cost of job - e.g. mark up on materials, profit on labour, mark up on buy ins, proportion of misc (less an amount that will actually be spent for finxings, etc., and so on.
After all that, it tells us two things - how profitable the job is, and how much room we have to move, should it be necessary.
Once the job is done, we compare the finished costs to the quoted costs, on an ongoing basis to make sure we're maintaining margin, etc. That's done in another sheet. We also, obviously monitor the margins on successful quotes, failed quotes, and so on too - to spot if we've gone in too high on particular work, or too low, - patterns develop over time.