Getting Started with WordPress Plugin Development: The Ultimate Guide (2015 Jan): https://premium.wpmudev.org/blog/wordpress-plugin-development-guide/

How To Create A WordPress Plugin (2014 Jul): https://www.elegantthemes.com/blog/tips-tricks/how-to-create-a-wordpress-plugin

Plugin API/Action Reference/the post: https://codex.wordpress.org/Plugin_API/Action_Reference/the_post#Example

Actions Run During a Typical Request: https://codex.wordpress.org/Plugin_API/Action_Reference

One drawback of WordPress development is that WordPress was released before PHP 5, so much of the WordPress code is procedural and can be difficult to organize.

PHP WordPress Plugin Tutorial using Object Oriented Programming Part 1: Advanced Features – Pak PHP Micro Framework package blog: http://www.phpclasses.org/blog/package/9505/post/2-PHP-WordPress-Plugin-Tutorial-using-Object-Oriented-Programming-Part-1-Advanced-Features.html

Contents
Introduction
How to Translate your plugin
How to Create a Simple Settings Page for your Plugin
How to create a Dashboard Widget
How to Make AJAX Calls
How to Create Custom Post Types and Taxonomies
How to Unit Test Your Plugin by Extending the WordPress XML-RPC interface
How to include third party scripts
Conclusion

PHP WordPress Plugin Tutorial using Object Oriented Programming Part 1: Basic Example – Pak PHP Micro Framework package blog: http://www.phpclasses.org/blog/package/9505/post/1-PHP-WordPress-Plugin-Tutorial-using-Object-Oriented-Programming-Part-1-Basic-Example.html

WordPress and Laravel: https://laravel-news.com/2016/01/wordpress-and-laravel/

A popular way of setting up a site like this is to use WordPress as the admin and then build out the frontend in a framework such as Laravel.

WordPress Corcel (under DEVelopment)

This way you can use WordPress as back-end, to insert posts, custom types, etc, and you can use what you want in front-end, like Silex, Slim Framework, Laravel, Zend, or even pure PHP (why not?).

Using WordPress with Lumen: http://adampatterson.ca/blog/2015/06/using-wordpress-with-lumen/

5 Tips for Dealing With Clients Who Won’t Pay: http://www.sitepoint.com/how-to-deal-with-non-paying-clients/

Even if you’re a one-person company, there’s no excuse for not having a clearly defined processes and policies for dealing with late payments.

How to Deal With a Non-Paying Client: http://www.1stwebdesigner.com/show-client-whos-boss/

We all would like to live in a perfect world. One without suffering, sickness and… annoying clients.

When a client won’t pay: http://www.the-haystack.com/2006/07/31/when-a-client-wont-pay/

Last week, for the very first time, I removed a client’s website from their host. The website has been up for over four months and we have yet to receive one cent in payment. In a saturated web development market in which our company (like many other small agencies) sometimes has to struggle to convince clients of the value of quality design and code (versus the “nephew with a copy of FrontPage”), we actually like to get paid for the work we do.

Dealing With Clients Who Refuse To Pay: http://www.smashingmagazine.com/2010/04/dealing-with-clients-who-refuse-to-pay/

The most unfortunate part of this unfortunate truth is that it will all too often present itself in the form of a client who refuses to pay for your services once all of the work has been completed.

Why we gave up web design after 10 successful years: https://silktide.com/why-we-gave-up-web-design-after-10-successful-years/
I fired a number of clients in our time, but you can’t fire everyone you disagree with. At times, to pay the bills, you’ll probably take on work you suspect you shouldn’t, and deal with people you wish you wouldn’t.

Why Don’t People Want To Pay For Good Design?: http://www.hongkiat.com/blog/paying-for-good-design/

People, at large, like to believe that they are creative on some level, even if their profession has absolutely nothing to do with design whatsoever.

Nem fizet a paraszt! – Szinte minden évben vagy egy olyan mocskos tróger, aki többszöri kérlelés, figyelmeztetés ellenére sem képes kifizetni az ember munkáját.: http://hup.hu/node/139996

“WordPress + Woocommerce: nem igényel többet. Eleve ez is volt a kérése a tisztelt megrendelőnek…”

Pénzbehajtás problémás ügyfelektől, hogyan?: http://weblabor.hu/forumok/temak/108816
Szerintem, a dolog ott van elcseszve, hogy csomóan üzembe helyezik az oldalt, mielőtt az ügyfél fizetne. Ráadásul az ügyfél szerverén, ahol nehéz korlátozni, ha nem fizet.

Honlapkészítés árak: http://www.eduwork.hu/honlap-k%C3%A9sz%C3%ADt%C3%A9s

Téveszmék a szoftverhibák kapcsán: http://infokukac.com/2010/07/teveszmek-a-szoftverhibak-kapcsan/

Simplicity of Google + Power of Bootstrap + Beauty of Material Design

Plenty of beautiful components

Plenty of useful templates

Easy installation

Easy to use and customize

Fully responsive (Perfect all on tablets, phones as well as desktops)

http://mdbootstrap.com/material-design-for-bootstrap/