diff --git a/smart_contracts_vulnerabilities/random-notes.md b/smart_contracts_vulnerabilities/random-notes.md
deleted file mode 100644
index c979b0e..0000000
--- a/smart_contracts_vulnerabilities/random-notes.md
+++ /dev/null
@@ -1,18 +0,0 @@
-## Random security notes
-
-<br>
-
-* `tx.origin` is used: you want to replace it by “msg.sender” because otherwise any contract you call can act on your behalf.
-* Avoid potential reetrancy bugs: 
-```
-msg.sender.transfer(amount);
-balances[msg.sender] -= amount;
-```
-* Inline assembly should be used only in rare cases.
-* Unclear semantics: `now` is alias for `block.timestamp` not current time; use of low level `call`, `callcode`, `delegatecall` should be avoided whenever possible; use `transfer` whenever failure of ether transfer should rollnack the whole transaction.
-* Beware of caller contracts: `selfdestruct` can block calling contracts unexpectedly.
-* Invocation of local functions via `this`: never use `this` to call functions in the same contract, it only consumes more gas than normal call.
-* Transferring Ether in a for/while/do-while loop should be avoid due to the block gas limit.
-* ERC20 `decimals` should have `uint8` as return type.
-
-<br>
diff --git a/smart_contracts_vulnerabilities/security_tips.md b/smart_contracts_vulnerabilities/security_tips.md
new file mode 100644
index 0000000..8efa20b
--- /dev/null
+++ b/smart_contracts_vulnerabilities/security_tips.md
@@ -0,0 +1,13 @@
+## 🌭 security tips
+
+<br>
+
+* `tx.origin` needs to bere placed by `msg.sender`, otherwise any contract you call can act on your behalf.
+* inline assembly should be used only in rare cases.
+* unclear semantics: `now` is alias for `block.timestamp` not current time; use of low level `call`, `callcode`, `delegatecall` should be avoided whenever possible; use `transfer` whenever failure of ether transfer should rollnack the whole transaction.
+* beware of caller contracts: `selfdestruct` can block calling contracts unexpectedly.
+* invocation of local functions via `this`: never use `this` to call functions in the same contract, it only consumes more gas than normal call.
+* transferring Ether in a for/while/do-while loop should be avoid due to the block gas limit.
+* erc20 `decimals` should have `uint8` as return type.
+
+<br>