There was a recent Tips for Providers thread, told from a client's perspective. I thought it only fair to give a related post from a provider's viewpoint.
1) Prioritize the support options. If a provider offers live support, only use this medium for inquiries or minor questions. During an outage or emergency, support members having to answer the same questions over and over to clients via live support will only delay them from solving the issue. If you have a concern regarding downtime, using the ticket system will not only keep the techs freed up to work on the problem, but will also serve as documentation should you need to claim SLA.
2) Maintain a respectful attitude. When you do interact with the company, be polite and courteous to the staff members. Not only does this further good relations with the company (nobody likes a client that does nothing but curse), but also prevents you from looking like a jackass should you decide to post on a public medium if an issue isn't resolved.
3) Be descriptive of any problems. Asking your provider "Sir why so lag" does absolutely nothing to help resolve a problem. If you're having latency issues, include a ping sample and a traceroute. If you can't get your VM to boot, explain what you've already tried instead of saying "It's down, fix it". Good communication is the key to getting a problem resolved quickly and efficiently.
4) Don't abuse the support systems. Opening multiple tickets about the same problem within a short period of time will not quicken the process. This only serves to irritate staff members. This also applies to live support; most companies answer tickets in the order they were received. Submitting a ticket and then immediately getting on live chat to tell them about your ticket (unless it's a true emergency) does not help.
5) The company is your provider, not your friend. Many companies maintain a friendly and outgoing presence in communities. You may even be on first-name basis with the owner or senior staff... this does not entitle you to ask for freebies, handouts, or exemptions to their policies. If we did it for you, we'd have to do it for everyone.
6) Be inquisitive, not accusatory Ties in to no2. If your VPS is offline, a ticket asking "Are there any issues with my node?" is much preferred to "Your service sucks fix it". You'll find that pleasant discourse will often get you much more informative answers about a problem than simply "It's working now".
7) Be aware of announcements. Many providers keep up-to-date announcements, as well as off-site presences such as Twitter, Facebook, or G+. Check these mediums regularly, especially before posting about downtime. The provider may have scheduled maintenance or other relevant information posted that would explain any problems you might currently have.
8) Don't immediately run to public forums. Goes with no7. Give a provider a chance to reply to your support inquiries before you blast them in public. Posting a "bad review" without even having a support ticket open is a sure way to find yourself with an eviction notice.
9) Make suggestions, but don't expect them all to happen. The best way for a host to provide quality service is to take into consideration the suggestions of their clients. Have an idea on how to improve a service, or a suggestion related to their website? Don't be afraid to speak up, but keep in mind that just because you suggested it doesn't mean it'll happen.
10) Be prompt with your invoices. You can save yourself a ton of headache simply by paying your invoices early. If you don't think you're going to make the due date, let the host know in advance, and they'll likely work with you. But, let's be honest... this is the LowEnd market. If you have to choose between paying another bill and paying for a 7$/mo VPS, then you really do not need a VPS.
11) READ. THE. TOS. Yeah, we all have a habit of blindly hitting "I accept the EULA" when installing a game or program. However, some VPS hosts out there are actually legitimate companies; when you sign up with them, you are entering a legal contract. If things turn bad enough (say, running up unpaid invoices or being terminated for abuse), there can be "real-world" repercussions for your actions (collections agencies don't care if you "didn't read the TOS, lol"). Read the service agreements, be sure to ask questions on anything you don't understand or would like clarification on. Don't agree with the no-refund policy? Don't sign up. Do you run a legitimate newsletter, but the provider frowns on SMTP? Get with them, explain the situation BEFORE you purchase, and see if they'll be fine with it.
There's probably more I could add, but I think that sums it up rather nicely. And to clarify; yes, I am a client of several hosts as well, so this is a summation of experience from both sides of the fence.