You can know the will of God by being led by the Spirit.  Then, the next question is this: "How can I know it is the Spirit and not myself?"

Here are five things you need to know about being led:

1. You must seek God on purpose
 Hebrews 11:6 God is and He is a rewarder—we will find Him if we seek Him.
 Matt 7:8  All who seek find
Luke 11:9-13 God will give the Holy Spirit, not a serpent or stone (evil spirit or human spirit).
2. You must not be double-minded mixing human reason with God’s leading
 James 1:8, 4:8  A double minded person does not have the mind of God, though they are trying to mix revelation with human-generated reason.  All that a double minded person really has is the natural mind alone.  The natural mind is the human mind that is deceitful and wicked.
 Luke 11:34, 2 Chronicles 15:15 You must be whole hearted—not double minded.  It is the office of the Holy Spirit to reveal.  Without a Holy and consecrated walk before God, it is impossible to have an understanding of the Holy Scriptures.
3. You will have a leading 
  This leading may be a word or a feeling or a vision.
  We have spiritual senses.
4. It will be Scriptural
 That which is in conflict with Scripture is not from God.
 That which is in conflict with the apostle’s doctrine is not from God.
5. The door will open.
 God never leads us where He doesn’t open the door.
 If a prophet prophecies and his prophecy doesn’t happen, don’t follow that prophet.  There are lots of authors who have predicted many things that didn't happen, and yet people keep buying their next lying book.  Amazing!
6. Walking in the Spirit brings forth the fruit of the Spirit.
 Matt 7:16-20 1 John 4:1-3, 1 Corinthians 12:3  If the spirit curses our brother and sister, it is not of God.  The Holy Spirit never tells us to sin or to do things outside of the will of God.
   We are the body of Christ and members in particular  

Gal 5:16-18  This I say then, Walk in the Spirit, and ye shall not fulfill the lust of the flesh.   For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would.   But if ye be led of the Spirit, ye are not under the law. [You don't need a law.  The Spirit leads you into holiness.]

If meditation, supplication, or prayer leads to the following, the flesh is leading:

Gal 5:19  Now the works of the flesh are manifest, which are these;
adultery,
fornication,  [perversion of marriage]
uncleanness,  [physical or moral]
lasciviousness, [lustfulness; wanton; lewd]
Gal 5:20 
Idolatry,  [worship of own self, own mind, possessions, power, etc.]
witchcraft,  [seek any but God for power or leading]
hatred,  [enmity, strong dislike]
variance,  [contention, debate, strife]
emulations, [indignation, jealousy, envy, being offended,]
wrath,  [anger--by the way, just try to find anything in the Bible about righteous anger other than from either the Father, the Son, Jesus, or the Holy Spirit.  Then think about all the false teaching you may have heard on this subject.]
strife, 
seditions,  [division]
heresies,  [disunion]
Gal 5:21 
Envyings,  [spite, wanting something bad to happen to someone—may be because they are blessed]
murders,
drunkenness,
revellings,  [obsession with entertainment and wild parties]
and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God.
Eph 4:31  Let all
bitterness,
and wrath, [fierceness]
and anger,  [indignation, vengeance, wrath]
and clamor,  [outcry]
and evil speaking, [To express objections or criticisms in bitter, harsh, or abusive language.]
be put away from you, with all malice: [a desire that others would come to harm.  For us, not praying for blessing on each other’s life and ministry.]

If meditation, supplication, or prayer leads to the following, the Spirit is leading:

Gal 5:22a  But the fruit of the Spirit is
love,

If we are called of God:
Heb 5:1-4  For every high priest taken from among men is ordained for men in things pertaining to God, that he may offer both gifts and sacrifices for sins:   Who can have compassion on the ignorant, and on them that are out of the way; for that he himself also is compassed with infirmity.  [we are]  And by reason hereof he ought, as for the people, so also for himself, to offer for sins.   And no man taketh this honor unto himself, but he that is called of God, as was Aaron.  [if we are called, this is what we do]

[if we come across one who is ignorant or out of the way (we all are sometimes), we must respond as priestly kings before God.]
Acts 7:60, Luke 23:34

Gal 5:22b joy,
peace,
longsuffering,
gentleness,
goodness,
faith,
Gal 5:23 
Meekness,
temperance:
against such there is no law.

Eph 4:32  And be ye kind one to another, tenderhearted,  [compassionate, sympathetic] forgiving one another, even as God for Christ's sake hath forgiven you.

Gal 5:24-6:10  And they that are Christ's have crucified the flesh with the affections and lusts.   If we live in the Spirit, let us also walk in the Spirit.   Let us not be desirous of vain glory, provoking one another, envying one another.   Brethren, if a man be overtaken in a fault, ye which are spiritual, restore such a one in the spirit of meekness; considering thyself, lest thou also be tempted.   Bear ye one another's burdens, and so fulfill the law of Christ.   For if a man think himself to be something, when he is nothing, he deceiveth himself.   But let every man prove his own work, and then shall he have rejoicing in himself alone, and not in another.   For every man shall bear his own burden.   Let him that is taught in the word communicate [literally: share or be partaker] unto him that teacheth in all good things [that is the Holy Spirit].   Be not deceived; God is not mocked: for whatsoever a man soweth, that shall he also reap.   For he that soweth to his flesh shall of the flesh reap corruption; but he that soweth to the Spirit shall of the Spirit reap life everlasting.   And let us not be weary in well doing: for in due season we shall reap, if we faint not.   As we have therefore opportunity, let us do good unto all men, especially unto them who are of the household of faith.