First of all, I think it's important to reserve all TLDs you can buy. If you can buy all TLDs for your domain, it's good pratice because you avoid future cyber squatting issues. If you can't buy all domain names, if I were you, I will buy at least
.org and TLDs of your country (
.us if you are in the US,
.be if you are in Belgium,
.co.uk if you are in the UK, etc.). After, you can choose primary domain and redirect (301 redirects) all to it. In order to choose primary domain, I like thinking country TLD (ccTLD) is good for business which stays in your country. For international business, I think
.com is the best choice because it's generic TLD.
Moreover, it's good pratice to think about visitors to build a web site because you can give them user-friendly experience. For this point, build short URLs and URLs easy to remember is good. Nice 404 page is also cool stuff.
www URLs, I advise you to choose one and to redirect (301 redirect) other to it. Example, if you choose
www.example.com traffic to
example.com. You can avoid duplicate content issues. It's also good to redirect
index.php to root domain name (example:
example.com) for same reason. In my experience, to help you, sites from the US like `no-www' URLs unlike sites from Europe but it's only in general.
I think you can choose to implement
https if your business is concerned by security. It depends on it. If you think it can help clients to understand your business is secure, it may be good idea to implement it.
Otherwise, thinking by user-friendly experience is good but thinking about SEO at the beginning is also good stuff for the future.