Conservative perspective is preservation of cultural traditions and norms. The appearance of self-serving motive is coincidental since the majority of conservatives directly benefit from the cultural traditions and norms they are trying to advocate and preserve. I'm sure there are self-serving conservatives protecting personal interests but not so many as to make the stereotype true. Conservatives are rarely interested in "what's best for me" and it would be accurate they believe their ideals are "best for everyone." The ideals are almost exclusively tied to tradition, not just usually.
Liberals are not concerned with what's best for all except for where they argue the single proposition that equally protected and applied individual freedoms and rights are best for all. The seeming diversity and openness of liberals is a consequence of their firm belief that individuals must be free to decide for themselves what ideals, traditions, and cultural norms to embrace. You'll see the vast majority of liberals are not open to creative solutions that require them to sacrifice personal liberty in exchange for some benefit.
That's about as general and simplified a summary I can manage. There are different sects and varying ideologies that fall under the labels conservative and liberal. Differences between individuals can be pretty extreme due to complex issues and differences in opinion.
But I'll re-summarize it as if I were explaining to a 5 years old...
Conservatives think that traditions and values they learned and follow are the reason good things happen to them and believe good things will happen for everyone who does and believes the same things they do. They truly believe if people just have faith and try it their way it will all work out for good.
Liberals think everyone is different, specially unique, and nothing is good for everyone the same way. They say a person can only know what is best for them and should never be forced to do something other people say is good for them if they disagree.