Question

For example if i’m using eric meyer reset and i have to apply this style to body.

body { font: 100%/1.5 "Helvetica Neue", Helvetica, Tahoma, Arial, sans-serif;*/ }

should i keep this before reset css or after?

html, body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, font, img, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td {
    margin: 0;
    padding: 0;
    border: 0;
    outline: 0;
    font-weight: inherit;
    font-style: inherit;
    font-size: 100%;
    font-family: inherit;
    vertical-align: baseline;
}
/* remember to define focus styles! */
:focus {
    outline: 0;
}
body {
    line-height: 1;
    color: black;
    background: white;
}
ol, ul {
    list-style: none;
}
/* tables still need 'cellspacing="0"' in the markup */
table {
    border-collapse: separate;
    border-spacing: 0;
}
caption, th, td {
    text-align: left;
    font-weight: normal;
}
blockquote:before, blockquote:after,
q:before, q:after {
    content: "";
}
blockquote, q {
    quotes: "" "";
}

Answer 1

If you don’t reset any font property that is set within your mentioned font rule, it doesn’t matter whether you put it before or after the reset as it won’t be altered by the reset.

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Edit    Now that I see what reset you’re using:

For the inherit values it’s regardless whether you’re using your font rule before or after the reset. So font-family ("Helvetica Neue", Helvetica, Tahoma, Arial, sans-serif) is the same for both variants. The same applies to properties that use the same values (font-size).

But the line-height values are different in both body rule sets (reset: 1; your rule: 1.5). And there you have to decide what value you want to have: If it’s 1, put your rule before the reset; if it’s 1.5 (and I guess so), put your rule after the reset.