There are a few things which you can do to prepare your quilt for quilting on the longarm machine. These things not only make life easier for the operator of the machine, but can often save you money too (depending on whether the quilter charges for "preparation time" prior to the quilt being loaded onto the rollers).
1. Ensure that your backing is big enough - I recommend that your backing is at least 10cm (or 4 inches) bigger around all the sides of the top. This means that the backing can be attached to the canvas leaders with ease and that there will be enough backing when the quilting gets to the end.
2. Make sure that your backing is square and sits flat - no puckers if you have joined pieces; the sides are straight and don't look like something the dog has chewed at; the selvedges have been cut off. Basically try and put as much care into the backing as the top - you will be disappointed if the top looks great but the backing lets the quilt down.
3. Ensure that your wadding is large enough - for all the same reasons as above. Also if you have to join wadding make sure it doesn't leave a seam which will be felt through the quilting - just butt the edges together and either hand or machine the pieces together.
4. Most longarm quilters are busy people - and time is money - so presenting your quilt rolled up in a ball in a plastic shopping bag means they will have to iron it and most will charge for this.
A better way is to iron the quilt top and backing before it leaves your home, ensuring the seams are ironed flat and the way they are supposed to go, then hang it onto a padded hanger. If you are sending by mail you can still do this, except fold the quilt and backing gently (without adding too many creases) before putting into the post pak. Usually then all the quilter has to do is wave the iron over any folding creases and then they are ready to go.
5. Have a think about what quilting designs you want on your quilt top - is it a present? What sort of things do you (or the recipient) like (hearts, flowers, straight lines, busy things, etc etc) and what colours do you like? Do you like the look of blending threads or contrasting threads? What sort of money do you want to spend - generally speaking the more "thinking" the quilter has to do and the more intricate the overall design, the more the quilting will cost.
Remember, if you say "Quilt what you think is best" then you will get what the quilter interprets your quilt top needs - it makes it easier if we have some kind of idea of what sort of effect you are looking for. After all, it is your "baby" and you have spent a lot of time and money buying the fabrics and making the quilt.
These are a few suggestions for preparing your quilt top. If you have any questions you are welcome to contact me.