If you see a contractors vehicle passing regularly through your area and they a clean and tidy vehicle then make a note of the number. The condition of their equipment and vehicles can be a tell tale sign of their aspirations for your new garden.
Once you are confident that they are not five minute wonders and you have established that they have a good reputation then give them a call.
Ask friends or family if they have used anyone in particular and if the contractor has done a good job. Word of mouth is a naturally good way to pass on good operators.Avoid cold callers to the door like the plague. If they come to you and especially if they give you a card with no address and just a mobile number then your on a loser instantly. Cold callers can be very intimidating and understandably some people, often the old, fall victim to their charm or aggressive style and more often than not they leave very shoddy workmanship.
Once you have established a likely source for your reputable contractor(s) then invite them round for a briefing. This in most cases should be informal and most definitely free (unless you are specifically asking for advice that you might agree is worth of a charge). A good rule of thumb is get three quotes/estimates.
Remember, a quote is binding by law but an estimate is just a guide and if you are not careful the final bill may rise with extras that are not foreseen.
Read terms and conditions in conjunction with estimates. For example I always say that the price for any excavations was to a depth of 1 metre. That is a reasonable depth because the contractor does not want to be liable for expensive corrective measures should he find something untoward.
I estimated to remove a large Rockery near Farnham. Under that Rockery was a large mound and I said to the client that I would estimate the price based on the mound being soil, I joked that I didn't want to be caught for any extra costs should I find an air raid shelter underneath.
You guessed it, it was exactly that and the concrete was so thick we had to leave it as the cost to remove it was too prohibitive for the client. In the end the top became a base for a new raised terrace.
Ask as many questions as you can and it is really worth typing out your specification with a sketch or a scaled drawing done by a garden designer to accompany your specs.
If your contractor knows his business he should be challenging as much of your design as possible. If you require a patio with retaining wall for example, he should be asking you if there are any services i.e. electricity, water, gas or drainage pipes running in the area of the proposed excavations. They should ask the route, the depth and so on and you will normally find that if they have prepared terms and conditions there will be reference to services.
A sensibly contractor will disclaim damage to underground services unless they are made aware of their exact location in advance. Some will do a CAT scan to locate if there is uncertainty but normally you will be responsible unless the contractor is negligent and you can show this, should there be a problem.
Establish the exact specification for the sub bases and footings. You may well express a desire for the sub bases to be a certain depth. Perhaps it is a cost consideration or just inexperience. A good contractor should be able to advise the depth of footing concrete for example based on instinct. Remember, if you specify something wrong and it is carried out to your instructions then you retain responsibility.
Also worth bearing in mind is your contractor should be worldly wise and whilst your plan or drawing may look good, does it actually work? Check dimensions and heights with him because your eye may tell you you need one step up onto the lawn but the tape measure never lies and it may well be three. This leads onto practicalities in getting equipment up onto the top lawn in the future. A bad back often occurs when you have to lift your bulky mower up and down steps every Saturday.
Take the access into consideration. The price of any work can dramatically rise if the contractor has to wheel several tonnes of materials along a side passage.
Estimate how long it takes to load a wheel barrow and wheel it to the back garden. A five minute round trip doesn't sound long but when you get fifty wheel barrows just to get the sand or soil round to where it is needed you have used half a day.
Once the contractor has taken your brief, advised you if he feels there may be shortfalls and verbally corrected them, he will go away and prepare a quotation or an estimate.
A good contractor will re-write a specification based on your initial brief. This serves two purposes. To protect him when the work is being executed as lack of written and agreed specifications leads to ill feeling or worse legal disputes should there be a disagreement.
It also means he doesn't have to do more than the specification. Lack of agreement on what both parties thought was being provided in the price can make a great deal of difference to the profit margins but also it means the contractor cannot skimp.
If the contractor returns the paperwork within a week then they are keen. If it takes 2-6 weeks and they need chasing then it is a tell tale of how they work. You do not want a contractor taking more time than is estimated and you certainly don’t want him to leave you in the lurch whilst he does another job at the same time as yours.
Overall, remember the contractor is your conduit to the next stage and that is having a successful and enjoyable garden. Plan wisely, think with your head and not with your heart. Read this article from the contractors perspective - How to select your client