Sample gulpfile.js good practice, ripped from https://github.com/yeoman/generator-gulp-webapp/blob/master/app/templates/gulpfile.js

gulpfile.js

'use strict';
// Generated on <%= (new Date).toISOString().split('T')[0] %> using <%= pkg.name %> <%= pkg.version %>

var gulp = require('gulp');
var open = require('open');
var wiredep = require('wiredep').stream;

// Load plugins
var $ = require('gulp-load-plugins')();

<% if (includeSass) { %>
// Styles
gulp.task('styles', function () {
    return gulp.src('app/styles/main.scss')
        .pipe($.rubySass({
          style: 'expanded',
          loadPath: ['app/bower_components']
        }))
        .pipe($.autoprefixer('last 1 version'))
        .pipe(gulp.dest('app/styles'))
        .pipe($.size());
});
<% } else { %>
// Styles
gulp.task('styles', function () {
    return gulp.src('app/styles/main.css')
        .pipe($.autoprefixer('last 1 version'))
        .pipe(gulp.dest('app/styles'))
        .pipe($.size());
});
<% } %>
// Scripts
gulp.task('scripts', function () {
    return gulp.src('app/scripts/**/*.js')
        .pipe($.jshint('.jshintrc'))
        .pipe($.jshint.reporter('default'))
        .pipe($.size());
});

// HTML
gulp.task('html', ['styles', 'scripts'], function () {
    var jsFilter = $.filter('**/*.js');
    var cssFilter = $.filter('**/*.css');

    return gulp.src('app/*.html')
        .pipe($.useref.assets())
        .pipe(jsFilter)
        .pipe($.uglify())
        .pipe(jsFilter.restore())
        .pipe(cssFilter)
        .pipe($.csso())
        .pipe(cssFilter.restore())
        .pipe($.useref.restore())
        .pipe($.useref())
        .pipe(gulp.dest('dist'))
        .pipe($.size());
});

// Images
gulp.task('images', function () {
    return gulp.src('app/images/**/*')
        .pipe($.cache($.imagemin({
            optimizationLevel: 3,
            progressive: true,
            interlaced: true
        })))
        .pipe(gulp.dest('dist/images'))
        .pipe($.size());
});

// Clean
gulp.task('clean', function () {
    return gulp.src(['dist/styles', 'dist/scripts', 'dist/images'], { read: false }).pipe($.clean());
});

// Build
gulp.task('build', ['html', 'images']);

// Default task
gulp.task('default', ['clean'], function () {
    gulp.start('build');
});

// Connect
gulp.task('connect', $.connect.server({
    root: ['app'],
    port: 9000,
    livereload: true
}));

// Open
gulp.task('serve', ['connect'<% if (includeSass) { %>, 'styles'<% } %>], function() {
  open("http://localhost:9000");
});

// Inject Bower components
gulp.task('wiredep', function () {
    gulp.src('app/styles/*.<% if (includeSass) { %>scss<% } else { %>css<% } %>')
        .pipe(wiredep({
            directory: 'app/bower_components',
            ignorePath: 'app/bower_components/'
        }))
        .pipe(gulp.dest('app/styles'));

    gulp.src('app/*.html')
        .pipe(wiredep({
            directory: 'app/bower_components',
            ignorePath: 'app/'
        }))
        .pipe(gulp.dest('app'));
});

// Watch
gulp.task('watch', ['connect', 'serve'], function () {
    // Watch for changes in `app` folder
    gulp.watch([
        'app/*.html',<% if (includeSass) { %>
        'app/styles/**/*.scss',<% } else { %>
        'app/styles/**/*.css',<% } %>
        'app/scripts/**/*.js',
        'app/images/**/*'
    ], function (event) {
        return gulp.src(event.path)
            .pipe($.connect.reload());
    });

    <% if (includeSass) { %>// Watch .scss files
    gulp.watch('app/styles/**/*.scss', ['styles']);

    <% } else { %>// Watch .css files
    gulp.watch('app/styles/**/*.css', ['styles']);

    <% }  %>// Watch .js files
    gulp.watch('app/scripts/**/*.js', ['scripts']);

    // Watch image files
    gulp.watch('app/images/**/*', ['images']);

    // Watch bower files
    gulp.watch('bower.json', ['wiredep']);
});