Developing the right skill set to be effective at sales takes time and, more importantly, the ability to learn from your mistakes or failures. If you're not reflecting after both a successful sale or an unsuccessful attempt with intent to determine what worked and what didn't, you're really doing yourself an injustice and dramatically reducing the possibility of improvement.

When you do actually take the time, here are five commonly made mistakes to pay particular attention to:

1. You’re too aggressive. Nobody likes to be strong-armed into buying something. This doesn’t mean that it can’t be done, in fact it happens regularly, but the reality is that you might close a single sale but will likely eliminate the possibility of future opportunity.

Related: To Win More Prospects, Stop Selling and Start Courting

So tone it down and work to get the person you’re selling to want to buy -- and not because they’re trying to get you to leave as quickly as possible.

2.  Selling a product, not a solution. If you’ve ever read a sales book, this isn’t a new concept, but it’s important to note because it’s a common mistake, particularly amongst new salespeople. Nobody buys products, they buy solutions to problems that they have.

For example, you don’t buy sliced bread because you have a great appreciation for grain-based products, you buy it because slicing bread off of a loaf is a pain and having it pre-sliced solves the problem.

Use this simple but effective thought process when developing your sales pitch. Sell solutions to problems, not products.

3. Not investing in whom you're selling to. Here’s a question: With respect to your biggest potential account, do you know the names of the children of the decision-maker? If not, it’s likely that you don’t have a real relationship with them, and as a result are going to struggle to close.

People naturally want to do business with people that they like and are personally connected to, which means that you need to invest time in creating real relationships with those to whom you’re attempting to sell to.

Related: 3 Books That Will Help Change The Way You Think About Sales

4. Chasing the impossible. Are you pursuing a “golden egg” account? You know, the one that has the ability to change the whole face of your company because of its incredible size and purchasing ability? Guess what? Every competitor in your space is vying for their attention and have been for quite some time, which means that you’re going to fight a long and arduous uphill battle just to get a meeting.

Instead of fighting your way upstream amongst all the other fish in the river, find the sales points that are sizable but more approachable and spend your time there. I’m not suggesting that you don’t go after the behemoths, but it’s really important that you balance your time with more reasonable offerings so you don’t find yourself dependent on a single account. More likely, you'll have none.

5. You've spoken negatively about your competitors. It’s easy to just tell the person that you’re selling to that your competitor is terrible because they make a bad product that doesn’t work.

That creates a list of problems: nobody likes dealing with negative people, you haven’t sold them a solution, the person you’re selling to likely has a great and personal relationship with the rep from the company you're bashing and business slander is real and has consequences -- yes, you’re liable for the things that come out of your mouth.

Instead, take the high road and sell your solutions above and beyond those of your competition, and better yet, invest the time to create a personal relationship to get the person you’re selling to want to buy your product -- not solely because of the problems your product solves, but because they like you personally and want to help.

Related: Lights, Camera, Sell? What Your Sales Team Can Learn from Actors.