POSTAGE
First Class is even cheaper than Media Mail on less than 16oz and way faster, I only use Media Mail when shipping more than a couple of books (Outbounds) at the same time. The other advantage of using first class or media mail instead of a Priority Box/Envelope or UPS it's purely aesthetic,
PACKAGING
I bought a bunch of kraft colored book-boxes from Uline.com (they have a wide selection of options in both boxes and envelopes) they are very cheap they have flexible size so you can ship one book or five with the same box, and you don't need backing. I do put the books in a self sealing poly bag to keep it dry. Keeping it with the "pretty box" theme you can print your labels using your own fonts and I even got post stamps made with the Outbound ship but this again is not essential at all just my artsy choices.
THE POST OFFICE
If you go to the post regularly here is my advice, try to go at off- peak times so you don't hug the counter for long, especially if you are shipping a lot or are not sure what you are doing (ie international shipping can be tricky with forms to fill out). Try to pay attention to the choices they offer you, and who is working there, some employees don't care and don't offer any choices resulting in more expensive rates, a good postal employee with help you find the cheapest more effective way to ship so if you find a good postal employee try to go when they are working it will save you a lot of money.
CHARGING
For the website paypal is the best option, and you can sell to anywhere in the world with it, just make sure to have an international option because shipping is a lot more expensive. I recommend having a button for each, book with shipping and may be one or two packages with a wide selection of books each. Paypal usps shipping is over complicated and leaves you with an ugly label. Try to keep it simple you can always have a form or email link so people can ask you what they want and you can charge them accordingly to their paypal email this is included with the free service. When you do the paypal button make sure to keep the code in a plain text file (you can keep it on your email just make sure to have the plain text option activated so the code doesn't get screwed, attachment is the safest). You can use this codes in as many pages as you want even in Blogger/Wordpress blogs. Try always to have the shipping rates to be higher rather than lower, otherwise you are losing money. A postal meter it's probably not necessary, for minis you can use a good kitchen scale to calculate your postage.
Here is some step by step of how I package and mail Outbounds:
STEP 1
Get you everything you need: Book, Bag, Box/Envelope, Return Label, Shipping Label, Goodies...
STEP 2
Bag it! I use self sealing poly bags because they fit Outbound perfectly and I don't have to tape them, but you can use comic book bags, regular bags or even food shrink wrap, I use this when shipping more than 2 books, it sticks to itself and it's very tight.
STEP 3
Box it: this Book Shipping boxes are the right size for this book, I secure it with some tape so it doesn't rattle around in the box but it doesn't really need it, the box also acts as backing, it has different folds so it "grows" depending on how many books you want to ship, keeping the books secure and squared.
STEP 4
Close the Box: This box is not self sealing but just packing tape will do the work, you can even go around the whole box a couple of times if you want to keep it secure for international shipping.
STEP 5
Label it: Return Address is very important, you can print Avery labels, I recommend to do it on a laser printed, that way if it gets wet and lost you will get it back eventually, if you don't have a laser printer you can print one sheet of return labels in regular white paper and then go to any place with a copy machine and copy this sheet into labels. There is FREE templates online to make sure they fit on each label, you can also buy labels then scan them and use that as your template, remember to take the scan out before you print it. I am using a sticker printer to do my labels. On the right you can see the custom postage I printed in Zazzle.com you can use your own image and put a custom value on them too, you can go up to $1.32 so that will be enough for most minis. The only downside is that you are paying more for postage, if you do it plan well and get lots of them so you don't pay too much more. It's really neat and if you don't have enough you can go to the post office and pay for the difference.
STEP 6
Print your shipping labels! You probably want to do this first so you know how many you are shipping but for this tutorial it's step 6. Same as the return label Avery self sticking labels are the easies best looking option, but if you want to save money you can use regular white paper and paste it to the box/envelope with a glue-stick. If you do custom font labels make sure it's clear and readable printed on black ink. If you want to make sure it will stay even when wet you can use a laser printer or put transparent tape on top of it. Also, I forgot! you can write it by hand but it takes longer and you can make mistakes. When making the labels I use Illustrator, I copy the name/address directly from the paypal email and paste it on the program so I don't type anything and end up shipping to Krakoa. As a last touch on this step I got this fancy scissors that make everything look pretty awesome so I give the labels a little style, don't skip this! is very important to the whole process.
STEP 7
Prettify! as you probably noted I try to make the package look good, most people will probably not care, but after getting a couple of packages from the UK, I want people to be happy to be getting a package from RBS, also it shows that a person did it even if you are printing the labels. Some times I will add a sketch or a little print or flyer to the package as a thanks. I also got some really old stamps that are worth 4c but feature some of NASAS very neat interplanetary vehicles (you can see them on Step 1). You can also get stamps made, they are fairly inexpensive with your return address or MEDIA MAIL or FIRST CLASS or even DO NOT BEND for when you are using envelopes.
I hope this helps, I try to make it enjoyable for me so it's doesn't feel like a chore and you can ship the books ASAP.