GENERAL STUFF
1.         Start early (but it’s never too late). 

2.         Find out what graduate school is really like. There are many unwritten rules and unstated expectations and realities. Talk to graduate students and professors about the activities and expectations of graduate school. Ask specifically what are the expectations and goals that might not be represented in a program guide. For example,
-              Grad school (and research) is hard work. It’s not a 9-5 job, and there typically isn’t much room for a major additional time commitment such as a job or a varsity level sport.
-              You will spend large amounts of time and energy devoted to writing, reading, thinking, learning, and feeling outside your comfort zone. You must do all this relatively independently.
-              Grad school also involves lots of time outside or in the lab, studying your system or your species, creating insights, collaborating, and feuling your passion for science.

3.         Think deeply about why you want to go to grad school in ecology. There are may reasons why people choose to go to graduate school, including a love of nature, a curiosity about research, love of science and desire for more training in scientific methods. Masters programs vary widely in terms of their emphasis on research, coursework, skill development, etc. Having a clear reason that you can articulate will help you choose the right program, supervisor and project, and help you get through the hard times in the middle of grad school. 

SOME COMMENTS SPECIFIC TO RESEARCH TRACK MASTERS AND PHD PROGRAMS
I will comment here on research-oriented masters and PHD programs. This program emphasizes research, not classes. The objective of graduate work is to lead a research project and produce a peer-reviewed publication.

Yes, a peer-reviewed publication. In research, there are expectations and standards set by the culture of the field you are joining. These expectations often substantially exceed the expectations formally outlined in a degree program on the university website or in the department handbook. For example, a typical MS program requires a thesis, written and submitted in a specific university format. However, to get a job or get into a good PHD program in ecological research, the expectation is actually that you have published (or are in the advanced stages of publishing) you work in a peer-reviewed scientific journal. The higher your sights on PHD programs, the better journal you want to get your work into. (Your mentors can guide you in the publication process).

Getting into a MS or PHD program. 
There is the program (e.g., UBC Zoology) and then there is the lab you join. The program has criteria for application, usually listed on the website. You need to follow these guidelines, including deadlines. But you also need to identify a supervisor whose lab you could join. This is a serious step that can take months. You want to find a supervisor who has space in their group for a new person. You want a supervisor and lab group that fits well with your interests and goals; a group who can help you achieve your goals and a group to which you bring something that will help them achieve their goals. A good fit might include
                  Research interests – do you want to do the kind of work the group does?
                  Professional goals – are your goals aligned with what the supervisor expects and can mentor?
                  Personality – can you get along with these people?
                  Experience. Do you have any experience with any part of the research? This is not necessary, but even some areas of common ground can help you and the supervisor evaluate whether you are a good fit. 
                  Independence*.  Have you demonstrated independence, motivation and the ability to complete major projects independently? A supervisor will be looking for this as they evaluate fit.

*a note on independence: Success in science requires independence and motivation to complete a project on a timeline. External deadlines are rare in science, yet scientists (and grad students) are expected to complete work in a timeline fashion. Supervisors are looking for evidence that applicants can do this, and the evidence they are looking for is for productivity outside of coursework. Classes provide deadlines.  Supervisors are looking for evidence of independent scholarship and leadership, where you had to apply a range of skills to complete a project. A large class project might suffice, but much better is a volunteer or directed studies research project in a research lab.

FUNDING. First, the good news: you get a salary while you’re in grad school. Yes, they pay you. Now, the bad news. It’s not much. But, you should not need to take out loans. More good/bad news: the money for your salary can come from a variety of sources, and the availability of funds can limit the ability of a supervisor to accept students. Knowing a little about how funding works, and that it’s important, can help you ask questions in the interview process, and understand when opportunities may or may not be available. Here are a few notes on how students might be funded.  
a)         Fellowships: Many countries, universities and departments offer fellowships to support graduate studies. You should ask potential supervisors, check websites, talk to grad students to find out about these. You should apply for any fellowships for which you are eligible, and ask for help with these applications. Find graduate students who have been successful with fellowships, ask for their advice.
b)        Supervisors may have funding from a grant to support a student doing a particular project. They will usually offer this if it’s available and relevant; very often supervisors do not have this kind of funding.
c)         Teaching assistant (TA) or research assistant (RA) positions. Many departments offer these positions to support students. At some universities, you can support yourself entirely on these positions. At other universities, these provide partial support, and additional salary is required from a fellowship or the supervisor. Discuss these options with each potential supervisor, grad students and departments to which you apply.

Bottom line: you have the best chance of getting into the program/lab you want if you have solid research experience and co-authorship on a peer-reviewed paper. Good letters of recommendation from a professor with whom you’ve worked (volunteered) are also important.

So, get involved in research early and often!
a)         volunteer in a lab. Graduate students almost always need a little help.
b)        Seize opportunities to help grad students with sample processing, field-work, literature review. This is a great way to get authorship on a paper.
c)         Learn R
d)        Work on your writing: develop good, regular writing habits.
e)         Don’t be shy! Approach researchers, ask questions, listen carefully and, most importantly, think creatively about what you love.

Good luck!
Here are some links to other articles and explanations of expectations for grad school: 
Charles Mitchell's lab at UNC. Charles provides great advice that applies not only to his lab, but to any top ecology group.
Stearns and Huey's Modest advice for graduate students. 

Expectations for my lab. If you’re interested in applying to work with me, here is an overview of my expectations, and what I will explore as we chat about grad school:
1)        You have done research and have some written product. Could be a report or thesis, but ideally is co-authorship on a paper.
2)        You can articulate why you want to go to grad school, why you want to join my group, and what are your thoughts for after grad school.
3)        You can discuss one or two research problems that really interest you and that you have thought about.
4)        You can work independently yet also can be an active contributor to our lab group.