The best way to keep standards high while getting good evals is to demonstrate respect and understanding for the students.
Absolutely. This is the single most important thing you can do. Show genuine concern for the students, and make sure they know that you CARE about them and are willing "go the extra mile" to help them succeed in the course.
There have been other threads on how to maximize evals:
[On edit: I was going to try to provide links, but you can follow kedves' suggestion to find past threads.]
A few specific things that help -- some of which have been posted previously on other threads:
1. As LarryC says, a little margarine helps. If you want to butter them up, at some point (close to eval time) spontaneously tell them what a great class they have been to work with, and how much you've enjoyed getting to know them. Hint that you somehow like them better than your past classes.
2. If you make everything available online at the beginning of the term, they will not appreciate it (i.e., take it for granted) and will probably make unreasonable demands for more online stuff that you don't want to prepare. So instead, try this:
Withhold a few course materials from your web site (review problems, practice exam, outline of topics to review for exam, useful links) and then reveal them one by one at a time when they will be most useful. Announce to the class, "I had a few requests" (even if you haven't) "...for some practice problems so I've put together a set of extra problems with solutions to help you prepare for the exam. They're now available on the course web site." The students will think you are being very responsive and doing extra work just for them.
2. Students ALWAYS want some sort of review sheet for exams. If you don't already have one, you can do this: take the detailed outline from your syllabus and replace it with a bare bones outline. Then hand out the detailed outline just before the midterm or final exam and call it an exam review sheet.
3. The next trick is almost like cheating; I try to avoid it but it works if the course evals are done before a substantial final exam. Give them a midterm exam that is fairly straightforward and a little easier than average. It makes them all feel like they are doing well in the class. Then you can "even things out" with a slightly harder final exam. [But don't slam them with a crazy-hard final. That's not nice.]
4. You can tweak your evals slightly by judiciously using keywords from the evaluation questions in class. Example: I used to get low marks for the item "Professor provides constructive feedback throughout the course". So now, every time I review homework or exams in class, I announce that I want to "take a few minutes to give some constructive feedback". My scores shot up even though I didn't really change anything.
If you can tell us exactly which items on the evals give you the most trouble, we can probably fine tune our suggestions to help.
Good luck!