My gulp workflow file

gulpfile.js

var gulp         = require('gulp');
var browserSync  = require('browser-sync');
var less         = require('gulp-less');
var autoprefixer = require('gulp-autoprefixer');
var minifyCSS    = require('gulp-minify-css');
var notify       = require('gulp-notify');
var gutil        = require('gulp-util');
var cp           = require('child_process');
var path         = require('path');
var uglify       = require('gulp-uglify');
var imagemin     = require('gulp-imagemin');
var pngquant     = require('imagemin-pngquant');


var messages = {
    jekyllBuild: '<span style="color: grey">Running:</span> $ jekyll build'
};

/**
 * Build the Jekyll Site
 */
gulp.task('jekyll-build', function (done) {
    browserSync.notify(messages.jekyllBuild);
    return cp.spawn('jekyll', ['build'], {stdio: 'inherit'})
        .on('close', done);
});

// minifiy js
gulp.task('compress', function() {
  gulp.src('js/*.js')
    .pipe(uglify())
    .pipe(gulp.dest('js/min'))
});

// minifiy images
gulp.task('images', function () {
    return gulp.src('images/*')
        .pipe(imagemin({
            progressive: true,
            svgoPlugins: [{removeViewBox: false}],
            use: [pngquant()]
        }))
        .pipe(gulp.dest('images'));
});

// compile LESS
gulp.task('less', function () {
  gulp.src('_less/main.less')
    .pipe(less({
      paths: [ path.join(__dirname, '_less', 'includes') ]
    }))
    .pipe(less({compress: true}).on('error', gutil.log))
    .pipe(autoprefixer('last 10 versions', 'ie 9'))
    .pipe(minifyCSS({keepBreaks: false}))
    .pipe(gulp.dest('css'))
    .pipe(notify('Less Compiled, Prefixed and Minified'));
});

// Watch files
gulp.task('watch', function () {
    gulp.watch('_less/**/*.less', ['less']);
    gulp.watch(['index.html', '_layouts/*.html', '_posts/*', '**/*.html', '_less/**/*.less', 'js/**/*', 'images/*'], ['jekyll-rebuild']);
});

gulp.task('default', ['browser-sync', 'images', 'watch', 'compress']);